class Delay(QWidget):
FRMT = 'zpk' # output format of delay filter widget
info ="""
**Delay widget**
allows entering the number of **delays** :math:`N` :math:`T_S`. It is treated as a FIR filter,
the number of delays is directly translated to a number of poles (:math:`N > 0`)
or zeros (:math:`N < 0`).
Obviously, there is no minimum design algorithm or no design algorithm at all :-)
"""
sig_tx = pyqtSignal(object)
def __init__(self):
QWidget.__init__(self)
self.N = 5
self.ft = 'FIR'
self.rt_dicts = ('com',)
self.rt_dict = {
'COM': {'man': {'fo':('a', 'N'),
'msg':('a',
"<span>Enter desired filter order <b><i>N</i></b>, corner "
"frequencies of pass and stop band(s), <b><i>F<sub>PB</sub></i></b>"
" and <b><i>F<sub>SB</sub></i></b> , and relative weight "
"values <b><i>W </i></b> (1 ... 10<sup>6</sup>) to specify how well "
"the bands are approximated.</span>")
},
},
'LP': {'man':{'wspecs': ('u','W_PB','W_SB'),
'tspecs': ('u', {'frq':('a','F_PB','F_SB'),
'amp':('u','A_PB','A_SB')})
},
},
'HP': {'man':{'wspecs': ('u','W_SB','W_PB')},
},
'BP': {
},
'BS': {'man':{'wspecs': ('u','W_PB','W_SB','W_PB2'),
'tspecs': ('u', {'frq':('a','F_PB','F_SB','F_SB2','F_PB2'),
'amp':('u','A_PB','A_SB','A_PB2')})
}
}
}
self.info_doc = []
#--------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter instance, fb.fil_inst.
"""
self.lbl_delay = QLabel("Delays", self)
self.lbl_delay.setObjectName('wdg_lbl_delays')
self.led_delay = QLineEdit(self)
self.led_delay.setText(str(self.N))
self.led_delay.setObjectName('wdg_led_delay')
self.led_delay.setToolTip("Number of delays, N > 0 produces poles, N < 0 zeros.")
self.layHWin = QHBoxLayout()
self.layHWin.setObjectName('wdg_layGWin')
self.layHWin.addWidget(self.lbl_delay)
self.layHWin.addWidget(self.led_delay)
self.layHWin.setContentsMargins(0,0,0,0)
# Widget containing all subwidgets (cmbBoxes, Labels, lineEdits)
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layHWin)
#----------------------------------------------------------------------
# SIGNALS & SLOTs
#----------------------------------------------------------------------
self.led_delay.editingFinished.connect(self._update_UI)
# fires when edited line looses focus or when RETURN is pressed
#----------------------------------------------------------------------
self._load_dict() # get initial / last setting from dictionary
self._update_UI()
def _update_UI(self):
"""
Update UI when line edit field is changed (here, only the text is read
and converted to integer) and store parameter settings in filter
dictionary
"""
self.N = safe_eval(self.led_delay.text(), self.N,
return_type='int')
self.led_delay.setText(str(self.N))
if not 'wdg_fil' in fb.fil[0]:
fb.fil[0].update({'wdg_fil':{}})
fb.fil[0]['wdg_fil'].update({'delay':
{'N':self.N}
})
# sig_tx -> select_filter -> filter_specs
self.sig_tx.emit({'sender':__name__, 'filt_changed':'delay'})
def _load_dict(self):
"""
Reload parameter(s) from filter dictionary (if they exist) and set
corresponding UI elements. _load_dict() is called upon initialization
and when the filter is loaded from disk.
"""
if 'wdg_fil' in fb.fil[0] and 'delay' in fb.fil[0]['wdg_fil']:
wdg_fil_par = fb.fil[0]['wdg_fil']['delay']
if 'N' in wdg_fil_par:
self.N = wdg_fil_par['N']
self.led_delay.setText(str(self.N))
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
"""
self.N = fil_dict['N'] # filter order is translated to numb. of delays
def _test_N(self):
"""
Warn the user if the calculated order is too high for a reasonable filter
design.
"""
if self.N > 2000:
return qfilter_warning(self, self.N, "Delay")
else:
return True
def _save(self, fil_dict, arg=None):
"""
Convert between poles / zeros / gain, filter coefficients (polynomes)
and second-order sections and store all available formats in the passed
dictionary 'fil_dict'.
"""
if arg is None:
arg = np.zeros(self.N)
fil_save(fil_dict, arg, self.FRMT, __name__)
def LPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict)
def HPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict)
def BPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict)
def BSman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict)
class Firwin(QWidget):
FRMT = 'ba' # output format(s) of filter design routines 'zpk' / 'ba' / 'sos'
# currently, only 'ba' is supported for firwin routines
sig_tx = pyqtSignal(
object) # local signal between FFT widget and FFTWin_Selector
sig_tx_local = pyqtSignal(object)
from pyfda.libs.pyfda_qt_lib import emit
def __init__(self):
QWidget.__init__(self)
self.ft = 'FIR'
win_names_list = [
"Boxcar", "Rectangular", "Barthann", "Bartlett", "Blackman",
"Blackmanharris", "Bohman", "Cosine", "Dolph-Chebyshev", "Flattop",
"General Gaussian", "Gauss", "Hamming", "Hann", "Kaiser",
"Nuttall", "Parzen", "Slepian", "Triangular", "Tukey"
]
self.cur_win_name = "Kaiser" # set initial window type
self.alg = "ichige"
# initialize windows dict with the list above for firwin window settings
self.win_dict = get_windows_dict(win_names_list=win_names_list,
cur_win_name=self.cur_win_name)
# get initial / last setting from dictionary, updating self.win_dict
self._load_dict()
# instantiate FFT window with windows dict
self.fft_widget = Plot_FFT_win(self,
win_dict=self.win_dict,
sym=True,
title="pyFDA FIR Window Viewer")
# hide window initially, this is modeless i.e. a non-blocking popup window
self.fft_widget.hide()
c = Common()
self.rt_dict = c.rt_base_iir
self.rt_dict_add = {
'COM': {
'min': {
'msg':
('a', "<br /><b>Note:</b> Filter order is only a rough "
"approximation and most likely far too low!")
},
'man': {
'msg':
('a', "Enter desired filter order <b><i>N</i></b> and "
"<b>-6 dB</b> pass band corner "
"frequency(ies) <b><i>F<sub>C</sub></i></b> .")
},
},
'LP': {
'man': {},
'min': {}
},
'HP': {
'man': {
'msg': ('a', r"<br /><b>Note:</b> Order needs to be odd!")
},
'min': {}
},
'BS': {
'man': {
'msg': ('a', r"<br /><b>Note:</b> Order needs to be odd!")
},
'min': {}
},
'BP': {
'man': {},
'min': {}
},
}
self.info = """**Windowed FIR filters**
are designed by truncating the
infinite impulse response of an ideal filter with a window function.
The kind of used window has strong influence on ripple etc. of the
resulting filter.
**Design routines:**
``scipy.signal.firwin()``
"""
# self.info_doc = [] is set in self._update_UI()
# ------------------- end of static info for filter tree ---------------
# ------------------------------------------------------------------------------
def process_sig_rx(self, dict_sig=None):
"""
Process local signals from / for
- FFT window widget
- qfft_win_select
"""
logger.debug("SIG_RX - vis: {0}\n{1}".format(self.isVisible(),
pprint_log(dict_sig)))
if dict_sig['id'] == id(self):
logger.warning(f"Stopped infinite loop:\n{pprint_log(dict_sig)}")
# --- signals coming from the FFT window widget or the qfft_win_select
if dict_sig['class'] in {'Plot_FFT_win', 'QFFTWinSelector'}:
if 'closeEvent' in dict_sig: # hide FFT window windget and return
self.hide_fft_wdg()
return
else:
if 'view_changed' in dict_sig and 'fft_win' in dict_sig[
'view_changed']:
# self._update_fft_window() # TODO: needed?
# local connection to FFT window widget and qfft_win_select
self.emit(dict_sig, sig_name='sig_tx_local')
# global connection to upper hierachies
# send notification that filter design has changed
self.emit({'filt_changed': 'firwin'})
# --------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter object, fb.filObj .
"""
# Combobox for selecting the algorithm to estimate minimum filter order
self.cmb_firwin_alg = QComboBox(self)
self.cmb_firwin_alg.setObjectName('wdg_cmb_firwin_alg')
self.cmb_firwin_alg.addItems(['ichige', 'kaiser', 'herrmann'])
# Minimum size, can be changed in the upper hierarchy levels using layouts:
self.cmb_firwin_alg.setSizeAdjustPolicy(QComboBox.AdjustToContents)
self.cmb_firwin_alg.hide()
self.qfft_win_select = QFFTWinSelector(self, self.win_dict)
# Minimum size, can be changed in the upper hierarchy levels using layouts:
# self.qfft_win_select.setSizeAdjustPolicy(QComboBox.AdjustToContents)
self.but_fft_wdg = QPushButton(self)
self.but_fft_wdg.setIcon(QIcon(":/fft.svg"))
but_height = self.qfft_win_select.sizeHint().height()
self.but_fft_wdg.setIconSize(QSize(but_height, but_height))
self.but_fft_wdg.setFixedSize(QSize(but_height, but_height))
self.but_fft_wdg.setToolTip(
'<span>Show / hide FFT widget (select window type '
' and display its properties).</span>')
self.but_fft_wdg.setCheckable(True)
self.but_fft_wdg.setChecked(False)
self.layHWin1 = QHBoxLayout()
# self.layHWin1.addWidget(self.cmb_firwin_win)
# self.layHWin1.addWidget(self.but_fft_wdg)
self.layHWin1.addWidget(self.cmb_firwin_alg)
self.layHWin2 = QHBoxLayout()
self.layHWin2.addWidget(self.but_fft_wdg)
self.layHWin2.addWidget(self.qfft_win_select)
self.layVWin = QVBoxLayout()
self.layVWin.addLayout(self.layHWin1)
self.layVWin.addLayout(self.layHWin2)
self.layVWin.setContentsMargins(0, 0, 0, 0)
# Widget containing all subwidgets (cmbBoxes, Labels, lineEdits)
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layVWin)
# ----------------------------------------------------------------------
# GLOBAL SIGNALS & SLOTs
# ----------------------------------------------------------------------
# connect FFT widget to qfft_selector and vice versa and to signals upstream:
self.fft_widget.sig_tx.connect(self.process_sig_rx)
self.qfft_win_select.sig_tx.connect(self.process_sig_rx)
# connect process_sig_rx output to both FFT widgets
self.sig_tx_local.connect(self.fft_widget.sig_rx)
self.sig_tx_local.connect(self.qfft_win_select.sig_rx)
# ----------------------------------------------------------------------
# SIGNALS & SLOTs
# ----------------------------------------------------------------------
self.cmb_firwin_alg.currentIndexChanged.connect(
self._update_fft_window)
self.but_fft_wdg.clicked.connect(self.toggle_fft_wdg)
# ----------------------------------------------------------------------
# ==============================================================================
def _update_fft_window(self):
""" Update window type for FirWin - unneeded at the moment """
self.alg = str(self.cmb_firwin_alg.currentText())
self.emit({'filt_changed': 'firwin'})
# --------------------------------------------------------------------------
def _load_dict(self):
"""
Reload window selection and parameters from filter dictionary
and set UI elements accordingly. load_dict() is called upon
initialization and when the filter is loaded from disk.
"""
self.N = fb.fil[0]['N']
# alg_idx = 0
if 'wdg_fil' in fb.fil[0] and 'firwin' in fb.fil[0]['wdg_fil']\
and type(fb.fil[0]['wdg_fil']['firwin']) is dict:
self.win_dict = fb.fil[0]['wdg_fil']['firwin']
self.emit({'view_changed': 'fft_win_type'}, sig_name='sig_tx_local')
# --------------------------------------------------------------------------
def _store_dict(self):
"""
Store window and parameter settings using `self.win_dict` in filter dictionary.
"""
if 'wdg_fil' not in fb.fil[0]:
fb.fil[0].update({'wdg_fil': {}})
fb.fil[0]['wdg_fil'].update({'firwin': self.win_dict})
# --------------------------------------------------------------------------
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
"""
self.N = fil_dict['N']
self.F_PB = fil_dict['F_PB']
self.F_SB = fil_dict['F_SB']
self.F_PB2 = fil_dict['F_PB2']
self.F_SB2 = fil_dict['F_SB2']
self.F_C = fil_dict['F_C']
self.F_C2 = fil_dict['F_C2']
# firwin amplitude specs are linear (not in dBs)
self.A_PB = fil_dict['A_PB']
self.A_PB2 = fil_dict['A_PB2']
self.A_SB = fil_dict['A_SB']
self.A_SB2 = fil_dict['A_SB2']
# self.alg = 'ichige' # algorithm for determining the minimum order
# self.alg = self.cmb_firwin_alg.currentText()
def _test_N(self):
"""
Warn the user if the calculated order is too high for a reasonable filter
design.
"""
if self.N > 1000:
return qfilter_warning(self, self.N, "FirWin")
else:
return True
def _save(self, fil_dict, arg):
"""
Convert between poles / zeros / gain, filter coefficients (polynomes)
and second-order sections and store all available formats in the passed
dictionary 'fil_dict'.
"""
fil_save(fil_dict, arg, self.FRMT, __name__)
try: # has the order been calculated by a "min" filter design?
fil_dict['N'] = self.N # yes, update filterbroker
except AttributeError:
pass
self._store_dict()
# ------------------------------------------------------------------------------
def firwin(self,
numtaps,
cutoff,
window=None,
pass_zero=True,
scale=True,
nyq=1.0,
fs=None):
"""
FIR filter design using the window method. This is more or less the
same as `scipy.signal.firwin` with the exception that an ndarray with
the window values can be passed as an alternative to the window name.
The parameters "width" (specifying a Kaiser window) and "fs" have been
omitted, they are not needed here.
This function computes the coefficients of a finite impulse response
filter. The filter will have linear phase; it will be Type I if
`numtaps` is odd and Type II if `numtaps` is even.
Type II filters always have zero response at the Nyquist rate, so a
ValueError exception is raised if firwin is called with `numtaps` even and
having a passband whose right end is at the Nyquist rate.
Parameters
----------
numtaps : int
Length of the filter (number of coefficients, i.e. the filter
order + 1). `numtaps` must be even if a passband includes the
Nyquist frequency.
cutoff : float or 1D array_like
Cutoff frequency of filter (expressed in the same units as `nyq`)
OR an array of cutoff frequencies (that is, band edges). In the
latter case, the frequencies in `cutoff` should be positive and
monotonically increasing between 0 and `nyq`. The values 0 and
`nyq` must not be included in `cutoff`.
window : ndarray or string
string: use the window with the passed name from scipy.signal.windows
ndarray: The window values - this is an addition to the original
firwin routine.
pass_zero : bool, optional
If True, the gain at the frequency 0 (i.e. the "DC gain") is 1.
Otherwise the DC gain is 0.
scale : bool, optional
Set to True to scale the coefficients so that the frequency
response is exactly unity at a certain frequency.
That frequency is either:
- 0 (DC) if the first passband starts at 0 (i.e. pass_zero
is True)
- `nyq` (the Nyquist rate) if the first passband ends at
`nyq` (i.e the filter is a single band highpass filter);
center of first passband otherwise
nyq : float, optional
Nyquist frequency. Each frequency in `cutoff` must be between 0
and `nyq`.
Returns
-------
h : (numtaps,) ndarray
Coefficients of length `numtaps` FIR filter.
Raises
------
ValueError
If any value in `cutoff` is less than or equal to 0 or greater
than or equal to `nyq`, if the values in `cutoff` are not strictly
monotonically increasing, or if `numtaps` is even but a passband
includes the Nyquist frequency.
See also
--------
scipy.firwin
"""
cutoff = np.atleast_1d(cutoff) / float(nyq)
# Check for invalid input.
if cutoff.ndim > 1:
raise ValueError("The cutoff argument must be at most "
"one-dimensional.")
if cutoff.size == 0:
raise ValueError("At least one cutoff frequency must be given.")
if cutoff.min() <= 0 or cutoff.max() >= 1:
raise ValueError(
"Invalid cutoff frequency {0}: frequencies must be "
"greater than 0 and less than nyq.".format(cutoff))
if np.any(np.diff(cutoff) <= 0):
raise ValueError("Invalid cutoff frequencies: the frequencies "
"must be strictly increasing.")
pass_nyquist = bool(cutoff.size & 1) ^ pass_zero
if pass_nyquist and numtaps % 2 == 0:
raise ValueError(
"A filter with an even number of coefficients must "
"have zero response at the Nyquist rate.")
# Insert 0 and/or 1 at the ends of cutoff so that the length of cutoff
# is even, and each pair in cutoff corresponds to passband.
cutoff = np.hstack(([0.0] * pass_zero, cutoff, [1.0] * pass_nyquist))
# `bands` is a 2D array; each row gives the left and right edges of
# a passband.
bands = cutoff.reshape(-1, 2)
# Build up the coefficients.
alpha = 0.5 * (numtaps - 1)
m = np.arange(0, numtaps) - alpha
h = 0
for left, right in bands:
h += right * sinc(right * m)
h -= left * sinc(left * m)
if type(window) == str:
# Get and apply the window function.
# from scipy.signal.signaltools import get_window
win = signaltools.get_window(window, numtaps, fftbins=False)
elif type(window) == np.ndarray:
win = window
else:
logger.error(
"The 'window' was neither a string nor a numpy array, "
"it could not be evaluated.")
return None
# apply the window function.
h *= win
# Now handle scaling if desired.
if scale:
# Get the first passband.
left, right = bands[0]
if left == 0:
scale_frequency = 0.0
elif right == 1:
scale_frequency = 1.0
else:
scale_frequency = 0.5 * (left + right)
c = np.cos(np.pi * m * scale_frequency)
s = np.sum(h * c)
h /= s
return h
def _firwin_ord(self, F, W, A, alg):
# http://www.mikroe.com/chapters/view/72/chapter-2-fir-filters/
delta_f = abs(F[1] - F[0]) * 2 # referred to f_Ny
# delta_A = np.sqrt(A[0] * A[1])
if "Kaiser" in self.win_dict and self.win_dict[
'cur_win_name'] == "Kaiser":
N, beta = sig.kaiserord(20 * np.log10(np.abs(fb.fil[0]['A_SB'])),
delta_f)
# logger.warning(f"N={N}, beta={beta}, A_SB={fb.fil[0]['A_SB']}")
self.win_dict["Kaiser"]["par"][0]["val"] = beta
self.qfft_win_select.led_win_par_0.setText(str(beta))
self.qfft_win_select.ui2dict_params(
) # pass changed parameter to other widgets
else:
N = remezord(F, W, A, fs=1, alg=alg)[0]
self.emit({'view_changed': 'fft_win_type'}, sig_name='sig_tx_local')
return N
def LPmin(self, fil_dict):
self._get_params(fil_dict)
self.N = self._firwin_ord([self.F_PB, self.F_SB], [1, 0],
[self.A_PB, self.A_SB],
alg=self.alg)
if not self._test_N():
return -1
fil_dict['F_C'] = (self.F_SB +
self.F_PB) / 2 # average calculated F_PB and F_SB
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
nyq=0.5,
window=self.qfft_win_select.get_window(self.N,
sym=True)))
def LPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
logger.warning(self.win_dict["cur_win_name"])
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
nyq=0.5,
window=self.qfft_win_select.get_window(self.N,
sym=True)))
def HPmin(self, fil_dict):
self._get_params(fil_dict)
N = self._firwin_ord([self.F_SB, self.F_PB], [0, 1],
[self.A_SB, self.A_PB],
alg=self.alg)
self.N = round_odd(N) # enforce odd order
if not self._test_N():
return -1
fil_dict['F_C'] = (self.F_SB +
self.F_PB) / 2 # average calculated F_PB and F_SB
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
pass_zero=False,
nyq=0.5,
window=self.qfft_win_select.get_window(self.N,
sym=True)))
def HPman(self, fil_dict):
self._get_params(fil_dict)
self.N = round_odd(self.N) # enforce odd order
if not self._test_N():
return -1
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
pass_zero=False,
nyq=0.5,
window=self.qfft_win_select.get_window(self.N,
sym=True)))
# For BP and BS, F_PB and F_SB have two elements each
def BPmin(self, fil_dict):
self._get_params(fil_dict)
self.N = remezord([self.F_SB, self.F_PB, self.F_PB2, self.F_SB2],
[0, 1, 0], [self.A_SB, self.A_PB, self.A_SB2],
fs=1,
alg=self.alg)[0]
if not self._test_N():
return -1
fil_dict['F_C'] = (self.F_SB +
self.F_PB) / 2 # average calculated F_PB and F_SB
fil_dict['F_C2'] = (self.F_SB2 + self.F_PB2) / 2
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
nyq=0.5,
pass_zero=False,
window=self.qfft_win_select.get_window(self.N,
sym=True)))
def BPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
nyq=0.5,
pass_zero=False,
window=self.qfft_win_select.get_window(self.N,
sym=True)))
def BSmin(self, fil_dict):
self._get_params(fil_dict)
N = remezord([self.F_PB, self.F_SB, self.F_SB2, self.F_PB2], [1, 0, 1],
[self.A_PB, self.A_SB, self.A_PB2],
fs=1,
alg=self.alg)[0]
self.N = round_odd(N) # enforce odd order
if not self._test_N():
return -1
fil_dict['F_C'] = (self.F_SB +
self.F_PB) / 2 # average calculated F_PB and F_SB
fil_dict['F_C2'] = (self.F_SB2 + self.F_PB2) / 2
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
window=self.qfft_win_select.get_window(self.N,
sym=True),
pass_zero=True,
nyq=0.5))
def BSman(self, fil_dict):
self._get_params(fil_dict)
self.N = round_odd(self.N) # enforce odd order
if not self._test_N():
return -1
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
window=self.qfft_win_select.get_window(self.N,
sym=True),
pass_zero=True,
nyq=0.5))
# ------------------------------------------------------------------------------
def toggle_fft_wdg(self):
"""
Show / hide FFT widget depending on the state of the corresponding button
When widget is shown, trigger an update of the window function.
"""
if self.but_fft_wdg.isChecked():
self.fft_widget.show()
self.emit({'view_changed': 'fft_win_type'},
sig_name='sig_tx_local')
else:
self.fft_widget.hide()
# --------------------------------------------------------------------------
def hide_fft_wdg(self):
"""
The closeEvent caused by clicking the "x" in the FFT widget is caught
there and routed here to only hide the window
"""
self.but_fft_wdg.setChecked(False)
self.fft_widget.hide()
class Firwin(QWidget):
FRMT = 'ba' # output format(s) of filter design routines 'zpk' / 'ba' / 'sos'
# currently, only 'ba' is supported for firwin routines
sig_tx = pyqtSignal(object)
def __init__(self):
QWidget.__init__(self)
self.ft = 'FIR'
self.fft_window = None
# dictionary for firwin window settings
self.win_dict = fb.fil[0]['win_fir']
c = Common()
self.rt_dict = c.rt_base_iir
self.rt_dict_add = {
'COM': {
'min': {
'msg':
('a',
r"<br /><b>Note:</b> Filter order is only a rough approximation "
"and most likely far too low!")
},
'man': {
'msg':
('a', r"Enter desired filter order <b><i>N</i></b> and "
"<b>-6 dB</b> pass band corner "
"frequency(ies) <b><i>F<sub>C</sub></i></b> .")
},
},
'LP': {
'man': {},
'min': {}
},
'HP': {
'man': {
'msg': ('a', r"<br /><b>Note:</b> Order needs to be odd!")
},
'min': {}
},
'BS': {
'man': {
'msg': ('a', r"<br /><b>Note:</b> Order needs to be odd!")
},
'min': {}
},
'BP': {
'man': {},
'min': {}
},
}
self.info = """**Windowed FIR filters**
are designed by truncating the
infinite impulse response of an ideal filter with a window function.
The kind of used window has strong influence on ripple etc. of the
resulting filter.
**Design routines:**
``scipy.signal.firwin()``
"""
#self.info_doc = [] is set in self._update_UI()
#------------------- end of static info for filter tree ---------------
#----------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter object, fb.filObj .
"""
# Combobox for selecting the algorithm to estimate minimum filter order
self.cmb_firwin_alg = QComboBox(self)
self.cmb_firwin_alg.setObjectName('wdg_cmb_firwin_alg')
self.cmb_firwin_alg.addItems(['ichige', 'kaiser', 'herrmann'])
# Minimum size, can be changed in the upper hierarchy levels using layouts:
self.cmb_firwin_alg.setSizeAdjustPolicy(QComboBox.AdjustToContents)
self.cmb_firwin_alg.hide()
# Combobox for selecting the window used for filter design
self.cmb_firwin_win = QComboBox(self)
self.cmb_firwin_win.addItems(get_window_names())
self.cmb_firwin_win.setObjectName('wdg_cmb_firwin_win')
# Minimum size, can be changed in the upper hierarchy levels using layouts:
self.cmb_firwin_win.setSizeAdjustPolicy(QComboBox.AdjustToContents)
self.but_fft_win = QPushButton(self)
self.but_fft_win.setText("WIN FFT")
self.but_fft_win.setToolTip(
"Show time and frequency response of FFT Window")
self.but_fft_win.setCheckable(True)
self.but_fft_win.setChecked(False)
self.lblWinPar1 = QLabel("a", self)
self.lblWinPar1.setObjectName('wdg_lbl_firwin_1')
self.ledWinPar1 = QLineEdit(self)
self.ledWinPar1.setText("0.5")
self.ledWinPar1.setObjectName('wdg_led_firwin_1')
self.lblWinPar1.setVisible(False)
self.ledWinPar1.setVisible(False)
self.lblWinPar2 = QLabel("b", self)
self.lblWinPar2.setObjectName('wdg_lbl_firwin_2')
self.ledWinPar2 = QLineEdit(self)
self.ledWinPar2.setText("0.5")
self.ledWinPar2.setObjectName('wdg_led_firwin_2')
self.ledWinPar2.setVisible(False)
self.lblWinPar2.setVisible(False)
self.layHWin1 = QHBoxLayout()
self.layHWin1.addWidget(self.cmb_firwin_win)
self.layHWin1.addWidget(self.but_fft_win)
self.layHWin1.addWidget(self.cmb_firwin_alg)
self.layHWin2 = QHBoxLayout()
self.layHWin2.addWidget(self.lblWinPar1)
self.layHWin2.addWidget(self.ledWinPar1)
self.layHWin2.addWidget(self.lblWinPar2)
self.layHWin2.addWidget(self.ledWinPar2)
self.layVWin = QVBoxLayout()
self.layVWin.addLayout(self.layHWin1)
self.layVWin.addLayout(self.layHWin2)
self.layVWin.setContentsMargins(0, 0, 0, 0)
# Widget containing all subwidgets (cmbBoxes, Labels, lineEdits)
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layVWin)
#----------------------------------------------------------------------
# SIGNALS & SLOTs
#----------------------------------------------------------------------
self.cmb_firwin_alg.activated.connect(self._update_win_fft)
self.cmb_firwin_win.activated.connect(self._update_win_fft)
self.ledWinPar1.editingFinished.connect(self._read_param1)
self.ledWinPar2.editingFinished.connect(self._read_param2)
self.but_fft_win.clicked.connect(self.show_fft_win)
#----------------------------------------------------------------------
self._load_dict() # get initial / last setting from dictionary
self._update_win_fft()
#=============================================================================
# Copied from impz()
#==============================================================================
def _read_param1(self):
"""Read out textbox when editing is finished and update dict and fft window"""
param = safe_eval(self.ledWinPar1.text(),
self.win_dict['par'][0]['val'],
sign='pos',
return_type='float')
if param < self.win_dict['par'][0]['min']:
param = self.win_dict['par'][0]['min']
elif param > self.win_dict['par'][0]['max']:
param = self.win_dict['par'][0]['max']
self.ledWinPar1.setText(str(param))
self.win_dict['par'][0]['val'] = param
self._update_win_fft()
def _read_param2(self):
"""Read out textbox when editing is finished and update dict and fft window"""
param = safe_eval(self.ledWinPar2.text(),
self.win_dict['par'][1]['val'],
return_type='float')
if param < self.win_dict['par'][1]['min']:
param = self.win_dict['par'][1]['min']
elif param > self.win_dict['par'][1]['max']:
param = self.win_dict['par'][1]['max']
self.ledWinPar2.setText(str(param))
self.win_dict['par'][1]['val'] = param
self._update_win_fft()
def _update_win_fft(self):
""" Update window type for FirWin """
self.alg = str(self.cmb_firwin_alg.currentText())
self.fir_window_name = qget_cmb_box(self.cmb_firwin_win, data=False)
self.win = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
n_par = self.win_dict['n_par']
self.lblWinPar1.setVisible(n_par > 0)
self.ledWinPar1.setVisible(n_par > 0)
self.lblWinPar2.setVisible(n_par > 1)
self.ledWinPar2.setVisible(n_par > 1)
if n_par > 0:
self.lblWinPar1.setText(
to_html(self.win_dict['par'][0]['name'] + " =", frmt='bi'))
self.ledWinPar1.setText(str(self.win_dict['par'][0]['val']))
self.ledWinPar1.setToolTip(self.win_dict['par'][0]['tooltip'])
if n_par > 1:
self.lblWinPar2.setText(
to_html(self.win_dict['par'][1]['name'] + " =", frmt='bi'))
self.ledWinPar2.setText(str(self.win_dict['par'][1]['val']))
self.ledWinPar2.setToolTip(self.win_dict['par'][1]['tooltip'])
# sig_tx -> select_filter -> filter_specs
self.sig_tx.emit({'sender': __name__, 'filt_changed': 'firwin'})
#=============================================================================
def _load_dict(self):
"""
Reload window selection and parameters from filter dictionary
and set UI elements accordingly. load_dict() is called upon
initialization and when the filter is loaded from disk.
"""
self.N = fb.fil[0]['N']
win_idx = 0
alg_idx = 0
if 'wdg_fil' in fb.fil[0] and 'firwin' in fb.fil[0]['wdg_fil']:
wdg_fil_par = fb.fil[0]['wdg_fil']['firwin']
if 'win' in wdg_fil_par:
if np.isscalar(
wdg_fil_par['win']): # true for strings (non-vectors)
window = wdg_fil_par['win']
else:
window = wdg_fil_par['win'][0]
self.ledWinPar1.setText(str(wdg_fil_par['win'][1]))
if len(wdg_fil_par['win']) > 2:
self.ledWinPar2.setText(str(wdg_fil_par['win'][2]))
# find index for window string
win_idx = self.cmb_firwin_win.findText(
window, Qt.MatchFixedString) # case insensitive flag
if win_idx == -1: # Key does not exist, use first entry instead
win_idx = 0
if 'alg' in wdg_fil_par:
alg_idx = self.cmb_firwin_alg.findText(wdg_fil_par['alg'],
Qt.MatchFixedString)
if alg_idx == -1: # Key does not exist, use first entry instead
alg_idx = 0
self.cmb_firwin_win.setCurrentIndex(
win_idx) # set index for window and
self.cmb_firwin_alg.setCurrentIndex(alg_idx) # and algorithm cmbBox
def _store_entries(self):
"""
Store window and alg. selection and parameter settings (part of
self.firWindow, if any) in filter dictionary.
"""
if not 'wdg_fil' in fb.fil[0]:
fb.fil[0].update({'wdg_fil': {}})
fb.fil[0]['wdg_fil'].update(
{'firwin': {
'win': self.firWindow,
'alg': self.alg
}})
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
"""
self.N = fil_dict['N']
self.F_PB = fil_dict['F_PB']
self.F_SB = fil_dict['F_SB']
self.F_PB2 = fil_dict['F_PB2']
self.F_SB2 = fil_dict['F_SB2']
self.F_C = fil_dict['F_C']
self.F_C2 = fil_dict['F_C2']
# firwin amplitude specs are linear (not in dBs)
self.A_PB = fil_dict['A_PB']
self.A_PB2 = fil_dict['A_PB2']
self.A_SB = fil_dict['A_SB']
self.A_SB2 = fil_dict['A_SB2']
# self.alg = 'ichige' # algorithm for determining the minimum order
# self.alg = self.cmb_firwin_alg.currentText()
def _test_N(self):
"""
Warn the user if the calculated order is too high for a reasonable filter
design.
"""
if self.N > 1000:
return qfilter_warning(self, self.N, "FirWin")
else:
return True
def _save(self, fil_dict, arg):
"""
Convert between poles / zeros / gain, filter coefficients (polynomes)
and second-order sections and store all available formats in the passed
dictionary 'fil_dict'.
"""
fil_save(fil_dict, arg, self.FRMT, __name__)
try: # has the order been calculated by a "min" filter design?
fil_dict['N'] = self.N # yes, update filterbroker
except AttributeError:
pass
# self._store_entries()
#------------------------------------------------------------------------------
def firwin(self,
numtaps,
cutoff,
window=None,
pass_zero=True,
scale=True,
nyq=1.0,
fs=None):
"""
FIR filter design using the window method. This is more or less the
same as `scipy.signal.firwin` with the exception that an ndarray with
the window values can be passed as an alternative to the window name.
The parameters "width" (specifying a Kaiser window) and "fs" have been
omitted, they are not needed here.
This function computes the coefficients of a finite impulse response
filter. The filter will have linear phase; it will be Type I if
`numtaps` is odd and Type II if `numtaps` is even.
Type II filters always have zero response at the Nyquist rate, so a
ValueError exception is raised if firwin is called with `numtaps` even and
having a passband whose right end is at the Nyquist rate.
Parameters
----------
numtaps : int
Length of the filter (number of coefficients, i.e. the filter
order + 1). `numtaps` must be even if a passband includes the
Nyquist frequency.
cutoff : float or 1D array_like
Cutoff frequency of filter (expressed in the same units as `nyq`)
OR an array of cutoff frequencies (that is, band edges). In the
latter case, the frequencies in `cutoff` should be positive and
monotonically increasing between 0 and `nyq`. The values 0 and
`nyq` must not be included in `cutoff`.
window : ndarray or string
string: use the window with the passed name from scipy.signal.windows
ndarray: The window values - this is an addition to the original
firwin routine.
pass_zero : bool, optional
If True, the gain at the frequency 0 (i.e. the "DC gain") is 1.
Otherwise the DC gain is 0.
scale : bool, optional
Set to True to scale the coefficients so that the frequency
response is exactly unity at a certain frequency.
That frequency is either:
- 0 (DC) if the first passband starts at 0 (i.e. pass_zero
is True)
- `nyq` (the Nyquist rate) if the first passband ends at
`nyq` (i.e the filter is a single band highpass filter);
center of first passband otherwise
nyq : float, optional
Nyquist frequency. Each frequency in `cutoff` must be between 0
and `nyq`.
Returns
-------
h : (numtaps,) ndarray
Coefficients of length `numtaps` FIR filter.
Raises
------
ValueError
If any value in `cutoff` is less than or equal to 0 or greater
than or equal to `nyq`, if the values in `cutoff` are not strictly
monotonically increasing, or if `numtaps` is even but a passband
includes the Nyquist frequency.
See also
--------
scipy.firwin
"""
cutoff = np.atleast_1d(cutoff) / float(nyq)
# Check for invalid input.
if cutoff.ndim > 1:
raise ValueError("The cutoff argument must be at most "
"one-dimensional.")
if cutoff.size == 0:
raise ValueError("At least one cutoff frequency must be given.")
if cutoff.min() <= 0 or cutoff.max() >= 1:
raise ValueError(
"Invalid cutoff frequency {0}: frequencies must be "
"greater than 0 and less than nyq.".format(cutoff))
if np.any(np.diff(cutoff) <= 0):
raise ValueError("Invalid cutoff frequencies: the frequencies "
"must be strictly increasing.")
pass_nyquist = bool(cutoff.size & 1) ^ pass_zero
if pass_nyquist and numtaps % 2 == 0:
raise ValueError(
"A filter with an even number of coefficients must "
"have zero response at the Nyquist rate.")
# Insert 0 and/or 1 at the ends of cutoff so that the length of cutoff
# is even, and each pair in cutoff corresponds to passband.
cutoff = np.hstack(([0.0] * pass_zero, cutoff, [1.0] * pass_nyquist))
# `bands` is a 2D array; each row gives the left and right edges of
# a passband.
bands = cutoff.reshape(-1, 2)
# Build up the coefficients.
alpha = 0.5 * (numtaps - 1)
m = np.arange(0, numtaps) - alpha
h = 0
for left, right in bands:
h += right * sinc(right * m)
h -= left * sinc(left * m)
if type(window) == str:
# Get and apply the window function.
from scipy.signal.signaltools import get_window
win = get_window(window, numtaps, fftbins=False)
elif type(window) == np.ndarray:
win = window
else:
logger.error(
"The 'window' was neither a string nor a numpy array, it could not be evaluated."
)
return None
# apply the window function.
h *= win
# Now handle scaling if desired.
if scale:
# Get the first passband.
left, right = bands[0]
if left == 0:
scale_frequency = 0.0
elif right == 1:
scale_frequency = 1.0
else:
scale_frequency = 0.5 * (left + right)
c = np.cos(np.pi * m * scale_frequency)
s = np.sum(h * c)
h /= s
return h
def _firwin_ord(self, F, W, A, alg):
#http://www.mikroe.com/chapters/view/72/chapter-2-fir-filters/
delta_f = abs(F[1] - F[0]) * 2 # referred to f_Ny
delta_A = np.sqrt(A[0] * A[1])
if self.fir_window_name == 'kaiser':
N, beta = sig.kaiserord(20 * np.log10(np.abs(fb.fil[0]['A_SB'])),
delta_f)
self.ledWinPar1.setText(str(beta))
fb.fil[0]['wdg_fil'][1] = beta
self._update_UI()
else:
N = remezord(F, W, A, fs=1, alg=alg)[0]
return N
def LPmin(self, fil_dict):
self._get_params(fil_dict)
self.N = self._firwin_ord([self.F_PB, self.F_SB], [1, 0],
[self.A_PB, self.A_SB],
alg=self.alg)
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
fil_dict['F_C'] = (self.F_SB + self.F_PB
) / 2 # use average of calculated F_PB and F_SB
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
window=self.fir_window,
nyq=0.5))
def LPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
window=self.fir_window,
nyq=0.5))
def HPmin(self, fil_dict):
self._get_params(fil_dict)
N = self._firwin_ord([self.F_SB, self.F_PB], [0, 1],
[self.A_SB, self.A_PB],
alg=self.alg)
self.N = round_odd(N) # enforce odd order
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
fil_dict['F_C'] = (self.F_SB + self.F_PB
) / 2 # use average of calculated F_PB and F_SB
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
window=self.fir_window,
pass_zero=False,
nyq=0.5))
def HPman(self, fil_dict):
self._get_params(fil_dict)
self.N = round_odd(self.N) # enforce odd order
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
self._save(
fil_dict,
self.firwin(self.N,
fil_dict['F_C'],
window=self.fir_window,
pass_zero=False,
nyq=0.5))
# For BP and BS, F_PB and F_SB have two elements each
def BPmin(self, fil_dict):
self._get_params(fil_dict)
self.N = remezord([self.F_SB, self.F_PB, self.F_PB2, self.F_SB2],
[0, 1, 0], [self.A_SB, self.A_PB, self.A_SB2],
fs=1,
alg=self.alg)[0]
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
fil_dict['F_C'] = (self.F_SB + self.F_PB
) / 2 # use average of calculated F_PB and F_SB
fil_dict['F_C2'] = (self.F_SB2 + self.F_PB2
) / 2 # use average of calculated F_PB and F_SB
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
window=self.fir_window,
pass_zero=False,
nyq=0.5))
def BPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
window=self.fir_window,
pass_zero=False,
nyq=0.5))
def BSmin(self, fil_dict):
self._get_params(fil_dict)
N = remezord([self.F_PB, self.F_SB, self.F_SB2, self.F_PB2], [1, 0, 1],
[self.A_PB, self.A_SB, self.A_PB2],
fs=1,
alg=self.alg)[0]
self.N = round_odd(N) # enforce odd order
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
fil_dict['F_C'] = (self.F_SB + self.F_PB
) / 2 # use average of calculated F_PB and F_SB
fil_dict['F_C2'] = (self.F_SB2 + self.F_PB2
) / 2 # use average of calculated F_PB and F_SB
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
window=self.fir_window,
pass_zero=True,
nyq=0.5))
def BSman(self, fil_dict):
self._get_params(fil_dict)
self.N = round_odd(self.N) # enforce odd order
if not self._test_N():
return -1
self.fir_window = calc_window_function(self.win_dict,
self.fir_window_name,
N=self.N,
sym=True)
self._save(
fil_dict,
self.firwin(self.N, [fil_dict['F_C'], fil_dict['F_C2']],
window=self.fir_window,
pass_zero=True,
nyq=0.5))
#------------------------------------------------------------------------------
def show_fft_win(self):
"""
Pop-up FFT window
"""
if self.but_fft_win.isChecked():
qstyle_widget(self.but_fft_win, "changed")
else:
qstyle_widget(self.but_fft_win, "normal")
if self.fft_window is None: # no handle to the window? Create a new instance
if self.but_fft_win.isChecked():
# important: Handle to window must be class attribute
# pass the name of the dictionary where parameters are stored and
# whether a symmetric window or one that can be continued periodically
# will be constructed
self.fft_window = Plot_FFT_win(self,
win_dict=self.win_dict,
sym=True,
title="pyFDA FIR Window Viewer")
self.sig_tx.connect(self.fft_window.sig_rx)
self.fft_window.sig_tx.connect(self.close_fft_win)
self.fft_window.show(
) # modeless i.e. non-blocking popup window
else:
if not self.but_fft_win.isChecked():
if self.fft_window is None:
logger.warning("FFT window is already closed!")
else:
self.fft_window.close()
def close_fft_win(self):
self.fft_window = None
self.but_fft_win.setChecked(False)
qstyle_widget(self.but_fft_win, "normal")
class AllpPZ(QWidget):
FRMT = 'zpk' # output format of delay filter widget
info = """
**Allpass widget**
allows entering the two **poles** :math:`p`. **zeros** are calculated from the
reciprocal values of the poles. There is no minimum algorithm, only the two
poles can be entered manually.
"""
sig_tx = pyqtSignal(object)
def __init__(self):
QWidget.__init__(self)
self.p = [0.5, 0.5j]
self.ft = 'IIR'
# the following defines which subwidgets are "a"ctive, "i"nvisible or "d"eactivated
self.rt_dicts = ('com', )
self.rt_dict = {
'COM': {
'man': {
'fo': ('d', 'N'),
'msg':
('a',
"<span>Enter poles <b><i>p</i></b> for allpass function,"
"zeros will be calculated.</span>")
},
},
'AP': {
'man': {}
}
}
self.info_doc = []
#--------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter instance, fb.fil_inst.
"""
self.lbl_pole1 = QLabel("Pole 1", self)
self.lbl_pole1.setObjectName('wdg_lbl_pole1')
self.led_pole1 = QLineEdit(self)
self.led_pole1.setText(str(self.p[0]))
self.led_pole1.setObjectName('wdg_led_pole1')
self.led_pole1.setToolTip("Pole 1 for allpass filter")
self.lbl_pole2 = QLabel("Pole 2", self)
self.lbl_pole2.setObjectName('wdg_lbl_pole2')
self.led_pole2 = QLineEdit(self)
self.led_pole2.setText(str(self.p[1]))
self.led_pole2.setObjectName('wdg_led_pole2')
self.led_pole2.setToolTip("Pole 2 for allpass filter")
self.layHWin = QHBoxLayout()
self.layHWin.setObjectName('wdg_layGWin')
self.layHWin.addWidget(self.lbl_pole1)
self.layHWin.addWidget(self.led_pole1)
self.layHWin.addWidget(self.lbl_pole2)
self.layHWin.addWidget(self.led_pole2)
self.layHWin.setContentsMargins(0, 0, 0, 0)
# Widget containing all subwidgets (cmbBoxes, Labels, lineEdits)
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layHWin)
#----------------------------------------------------------------------
# SIGNALS & SLOTs
#----------------------------------------------------------------------
self.led_pole1.editingFinished.connect(self._update_UI)
self.led_pole2.editingFinished.connect(self._update_UI)
# fires when edited line looses focus or when RETURN is pressed
#----------------------------------------------------------------------
self._load_dict() # get initial / last setting from dictionary
self._update_UI()
def _update_UI(self):
"""
Update UI when line edit field is changed (here, only the text is read
and converted to integer) and store parameter settings in filter
dictionary
"""
self.p[0] = safe_eval(self.led_pole1.text(),
self.p[0],
return_type='cmplx')
self.led_pole1.setText(str(self.p[0]))
self.p[1] = safe_eval(self.led_pole2.text(),
self.p[1],
return_type='cmplx')
self.led_pole2.setText(str(self.p[1]))
if not 'wdg_fil' in fb.fil[0]:
fb.fil[0].update({'wdg_fil': {}})
fb.fil[0]['wdg_fil'].update(
{'poles': {
'p1': self.p[0],
'p2': self.p[1]
}})
# sig_tx -> select_filter -> filter_specs
self.sig_tx.emit({'sender': __name__, 'filt_changed': 'pole_1_2'})
def _load_dict(self):
"""
Reload parameter(s) from filter dictionary (if they exist) and set
corresponding UI elements. _load_dict() is called upon initialization
and when the filter is loaded from disk.
"""
if 'wdg_fil' in fb.fil[0] and 'poles' in fb.fil[0]['wdg_fil']:
wdg_fil_par = fb.fil[0]['wdg_fil']['poles']
if 'p1' in wdg_fil_par:
self.p1 = wdg_fil_par['p1']
self.led_pole1.setText(str(self.p1))
if 'p2' in wdg_fil_par:
self.p2 = wdg_fil_par['p2']
self.led_pole2.setText(str(self.p2))
def _get_params(self, fil_dict):
"""
Get parameters needed for filter design from the passed dictionary and
translate them to instance parameters, scaling / transforming them if needed.
"""
#self.p1 = fil_dict['zpk'][1][0] # get the first and second pole
#self.p2 = fil_dict['zpk'][1][1] # from central filter dect
logger.info(fil_dict['zpk'])
def _test_poles(self):
"""
Warn the user if one of the poles is outside the unit circle
"""
if abs(self.p[0]) >= 1 or abs(self.p[1]) >= 1:
return qfilter_warning(self, self.p[0], "Delay")
else:
return True
def _save(self, fil_dict, arg=None):
"""
Convert between poles / zeros / gain, filter coefficients (polynomes)
and second-order sections and store all available formats in the passed
dictionary 'fil_dict'.
"""
if arg is None:
logger.error("Passed empty filter dict")
logger.info(arg)
fil_save(fil_dict, arg, self.FRMT, __name__)
fil_dict['N'] = len(self.p)
#------------------------------------------------------------------------------
# Filter design routines
#------------------------------------------------------------------------------
# The method name MUST be "FilterType"+"MinMan", e.g. LPmin or BPman
def APman(self, fil_dict):
"""
Calculate z =1/p* for a given set of poles p. If p=0, set z=0.
The gain factor k is calculated from z and p at z = 1.
"""
self._get_params(fil_dict) # not needed here
if not self._test_poles():
return -1
self.z = [0, 0]
if self.p[0] != 0:
self.z[0] = np.conj(1 / self.p[0])
if type(self.p[0]) == complex:
pass
if self.p[1] != 0:
self.z[1] = np.conj(1 / self.p[1])
k = np.abs(
np.polyval(np.poly(self.p), 1) / np.polyval(np.poly(self.z), 1))
zpk_list = [self.z, self.p, k]
self._save(fil_dict, zpk_list)
class EllipZeroPhz(QWidget):
# Since we are also using poles/residues -> let's force zpk
# if SOS_AVAIL:
# output format of filter design routines 'zpk' / 'ba' / 'sos'
# FRMT = 'sos'
# else:
FRMT = 'zpk'
info = """
**Elliptic filters with zero phase**
(also known as Cauer filters) have the steepest rate of transition between the
frequency response’s passband and stopband of all IIR filters. This comes
at the expense of a constant ripple (equiripple) :math:`A_PB` and :math:`A_SB`
in both pass and stop band. Ringing of the step response is increased in
comparison to Chebychev filters.
As the passband ripple :math:`A_PB` approaches 0, the elliptical filter becomes
a Chebyshev type II filter. As the stopband ripple :math:`A_SB` approaches 0,
it becomes a Chebyshev type I filter. As both approach 0, becomes a Butterworth
filter (butter).
For the filter design, the order :math:`N`, minimum stopband attenuation
:math:`A_SB` and the critical frequency / frequencies :math:`F_PB` where the
gain first drops below the maximum passband ripple :math:`-A_PB` have to be specified.
The ``ellipord()`` helper routine calculates the minimum order :math:`N` and
critical passband frequency :math:`F_C` from pass and stop band specifications.
The Zero Phase Elliptic Filter squares an elliptic filter designed in
a way to produce the required Amplitude specifications. So initially the
amplitude specs design an elliptic filter with the square root of the amp specs.
The filter is then squared to produce a zero phase filter.
The filter coefficients are applied to the signal data in a backward and forward
time fashion. This filter can only be applied to stored signal data (not
real-time streaming data that comes in a forward time order).
We are forcing the order N of the filter to be even. This simplifies the poles/zeros
to be complex (no real values).
**Design routines:**
``scipy.signal.ellip()``, ``scipy.signal.ellipord()``
"""
sig_tx = pyqtSignal(object)
def __init__(self):
QWidget.__init__(self)
self.ft = 'IIR'
c = Common()
self.rt_dict = c.rt_base_iir
self.rt_dict_add = {
'COM':{'man':{'msg':('a',
"Enter the filter order <b><i>N</i></b>, the minimum stop "
"band attenuation <b><i>A<sub>SB</sub></i></b> and frequency or "
"frequencies <b><i>F<sub>C</sub></i></b> where gain first drops "
"below the max passband ripple <b><i>-A<sub>PB</sub></i></b> .")}},
'LP': {'man':{}, 'min':{}},
'HP': {'man':{}, 'min':{}},
'BS': {'man':{}, 'min':{}},
'BP': {'man':{}, 'min':{}},
}
self.info_doc = []
self.info_doc.append('ellip()\n========')
self.info_doc.append(sig.ellip.__doc__)
self.info_doc.append('ellipord()\n==========')
self.info_doc.append(ellipord.__doc__)
#--------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter instance, fb.fil_inst.
"""
self.chkComplex = QCheckBox("ComplexFilter", self)
self.chkComplex.setToolTip("Designs BP or BS Filter for complex data.")
self.chkComplex.setObjectName('wdg_lbl_el')
self.chkComplex.setChecked(False)
#--------------------------------------------------
# Layout for filter optional subwidgets
self.layHWin = QHBoxLayout()
self.layHWin.setObjectName('wdg_layGWin')
#self.layHWin.addWidget(self.chkComplex)
self.layHWin.addStretch()
self.layHWin.setContentsMargins(0,0,0,0)
# Widget containing all subwidgets
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layHWin)
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
For zero phase filter, we take square root of amplitude specs
since we later square filter. Define design around smallest amp spec
"""
# Frequencies are normalized to f_Nyq = f_S/2, ripple specs are in dB
self.analog = False # set to True for analog filters
self.manual = False # default is normal design
self.N = int(fil_dict['N'])
# force N to be even
if (self.N % 2) == 1:
self.N += 1
self.F_PB = fil_dict['F_PB'] * 2
self.F_SB = fil_dict['F_SB'] * 2
self.F_PB2 = fil_dict['F_PB2'] * 2
self.F_SB2 = fil_dict['F_SB2'] * 2
self.F_PBC = None
# find smallest spec'd linear value and rewrite dictionary
ampPB = fil_dict['A_PB']
ampSB = fil_dict['A_SB']
# take square roots of amp specs so resulting squared
# filter will meet specifications
if (ampPB < ampSB):
ampSB = sqrt(ampPB)
ampPB = sqrt(1+ampPB)-1
else:
ampPB = sqrt(1+ampSB)-1
ampSB = sqrt(ampSB)
self.A_PB = lin2unit(ampPB, 'IIR', 'A_PB', unit='dB')
self.A_SB = lin2unit(ampSB, 'IIR', 'A_SB', unit='dB')
#logger.warning("design with "+str(self.A_PB)+","+str(self.A_SB))
# ellip filter routines support only one amplitude spec for
# pass- and stop band each
if str(fil_dict['rt']) == 'BS':
fil_dict['A_PB2'] = self.A_PB
elif str(fil_dict['rt']) == 'BP':
fil_dict['A_SB2'] = self.A_SB
# partial fraction expansion to define residue vector
def _partial(self, k, p, z, norder):
# create diff array
diff = p - z
# now compute residual vector
cone = complex(1.,0.)
residues = zeros(norder, complex)
for i in range(norder):
residues[i] = k * (diff[i] / p[i])
for j in range(norder):
if (j != i):
residues[i] = residues[i] * (cone + diff[j]/(p[i] - p[j]))
# now compute DC term for new expansion
sumRes = 0.
for i in range(norder):
sumRes = sumRes + residues[i].real
dc = k - sumRes
return (dc, residues)
#
# Take a causal filter and square it. The result has the square
# of the amplitude response of the input, and zero phase. Filter
# is noncausal.
# Input:
# k - gain in pole/zero form
# p - numpy array of poles
# z - numpy array of zeros
# g - gain in pole/residue form
# r - numpy array of residues
# nn- order of filter
# Output:
# kn - new gain (pole/zero)
# pn - new poles
# zn - new zeros (numpy array)
# gn - new gain (pole/residue)
# rn - new residues
def _sqCausal (self, k, p, z, g, r, nn):
# Anticausal poles have conjugate-reciprocal symmetry
# Starting anticausal residues are conjugates (adjusted below)
pA = conj(1./p) # antiCausal poles
zA = conj(z) # antiCausal zeros (store reciprocal)
rA = conj(r) # antiCausal residues (to start)
rC = zeros(nn, complex)
# Adjust residues. Causal part first.
for j in range(nn):
# Evaluate the anticausal filter at each causal pole
tmpx = rA / (1. - p[j]/pA)
ztmp = g + sum(tmpx)
# Adjust residue
rC[j] = r[j]*ztmp
# anticausal residues are just conjugates of causal residues
# r3 = np.conj(r2)
# Compute the constant term
dc2 = (g + sum(r))*g - sum(rC)
# Populate output (2nn elements)
gn = dc2.real
# Drop complex poles/residues in LHP, keep only UHP
pA = conj(p) #store AntiCasual pole (reciprocal)
p0 = zeros(int(nn/2), complex)
r0 = zeros(int(nn/2), complex)
cnt = 0
for j in range(nn):
if (p[j].imag > 0.0):
p0[cnt] = p[j]
r0[cnt] = rC[j]
cnt = cnt+1
# Let operator know we squared filter
# logger.info('After squaring filter, order: '+str(nn*2))
# For now and our case, only store causal residues
# Filters are symmetric and can generate antiCausal residues
return (pA, zA, gn, p0, r0)
def _test_N(self):
"""
Warn the user if the calculated order is too high for a reasonable filter
design.
"""
if self.N > 30:
return qfilter_warning(self, self.N, "Zero-phase Elliptic")
else:
return True
# custom save of filter dictionary
def _save(self, fil_dict, arg):
"""
First design initial elliptic filter meeting sqRoot Amp specs;
- Then create residue vector from poles/zeros;
- Then square filter (k,p,z and dc,p,r) to get zero phase filter;
- Then Convert results of filter design to all available formats (pz, pr, ba, sos)
and store them in the global filter dictionary.
Corner frequencies and order calculated for minimum filter order are
also stored to allow for an easy subsequent manual filter optimization.
"""
fil_save(fil_dict, arg, self.FRMT, __name__)
# For min. filter order algorithms, update filter dict with calculated
# new values for filter order N and corner frequency(s) F_PBC
fil_dict['N'] = self.N
if str(fil_dict['fo']) == 'min':
if str(fil_dict['rt']) == 'LP' or str(fil_dict['rt']) == 'HP':
# HP or LP - single corner frequency
fil_dict['F_PB'] = self.F_PBC / 2.
else: # BP or BS - two corner frequencies
fil_dict['F_PB'] = self.F_PBC[0] / 2.
fil_dict['F_PB2'] = self.F_PBC[1] / 2.
# Now generate poles/residues for custom file save of new parameters
if (not self.manual):
z = fil_dict['zpk'][0]
p = fil_dict['zpk'][1]
k = fil_dict['zpk'][2]
n = len(z)
gain, residues = self._partial (k, p, z, n)
pA, zA, gn, pC, rC = self._sqCausal (k, p, z, gain, residues, n)
fil_dict['rpk'] = [rC, pC, gn]
# save antiCausal b,a (nonReciprocal) also [easier to compute h(n)
try:
fil_dict['baA'] = sig.zpk2tf(zA, pA, k)
except Exception as e:
logger.error(e)
# 'rpk' is our signal that this is a non-Causal filter with zero phase
# inserted into fil dictionary after fil_save and convert
# sig_tx -> select_filter -> filter_specs
self.sig_tx.emit({'sender':__name__, 'filt_changed':'ellip_zero'})
#------------------------------------------------------------------------------
#
# DESIGN ROUTINES
#
#------------------------------------------------------------------------------
# LP: F_PB < F_stop -------------------------------------------------------
def LPmin(self, fil_dict):
"""Elliptic LP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,self.F_SB, self.A_PB,self.A_SB, analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
#logger.warning("and "+str(self.F_PBC) + " " + str(self.N))
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='low', analog=self.analog, output=self.FRMT))
def LPman(self, fil_dict):
"""Elliptic LP filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PB,
btype='low', analog=self.analog, output=self.FRMT))
# HP: F_stop < F_PB -------------------------------------------------------
def HPmin(self, fil_dict):
"""Elliptic HP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,self.F_SB, self.A_PB,self.A_SB,
analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='highpass', analog=self.analog, output=self.FRMT))
def HPman(self, fil_dict):
"""Elliptic HP filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PB,
btype='highpass', analog=self.analog, output=self.FRMT))
# For BP and BS, F_XX have two elements each, A_XX has only one
# BP: F_SB[0] < F_PB[0], F_SB[1] > F_PB[1] --------------------------------
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB, self.A_SB, analog=self.analog)
#logger.warning(" "+str(self.F_PBC) + " " + str(self.N))
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
#logger.warning("-"+str(self.F_PBC) + " " + str(self.A_SB))
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandpass', analog=self.analog, output=self.FRMT))
def BPman(self, fil_dict):
"""Elliptic BP filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB,
[self.F_PB,self.F_PB2], btype='bandpass', analog=self.analog,
output=self.FRMT))
# BS: F_SB[0] > F_PB[0], F_SB[1] < F_PB[1] --------------------------------
def BSmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2], self.A_PB,self.A_SB, analog=self.analog)
# force even N
if (self.N%2)== 1:
self.N += 1
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB, self.F_PBC,
btype='bandstop', analog=self.analog, output=self.FRMT))
def BSman(self, fil_dict):
"""Elliptic BS filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(fil_dict, sig.ellip(self.N, self.A_PB, self.A_SB,
[self.F_PB,self.F_PB2], btype='bandstop', analog=self.analog,
output=self.FRMT))
class MA(QWidget):
FRMT = (
'zpk', 'ba'
) # output format(s) of filter design routines 'zpk' / 'ba' / 'sos'
info = """
**Moving average filters**
can only be specified via their length and the number of cascaded sections.
The minimum order to obtain a certain attenuation at a given frequency is
calculated via the si function.
Moving average filters can be implemented very efficiently in hard- and software
as they require no multiplications but only addition and subtractions. Probably
only the lowpass is really useful, as the other response types only filter out resp.
leave components at ``f_S/4`` (bandstop resp. bandpass) resp. leave components
near ``f_S/2`` (highpass).
**Design routines:**
``ma.calc_ma()``
"""
sig_tx = pyqtSignal(object)
from pyfda.libs.pyfda_qt_lib import emit
def __init__(self):
QWidget.__init__(self)
self.delays = 12 # number of delays per stage
self.stages = 1 # number of stages
self.ft = 'FIR'
self.rt_dicts = ()
# Common data for all filter response types:
# This data is merged with the entries for individual response types
# (common data comes first):
self.rt_dict = {
'COM': {
'man': {
'fo': ('d', 'N'),
'msg':
('a',
"Enter desired order (= delays) <b><i>M</i></b> per stage and"
" the number of <b>stages</b>. Target frequencies and amplitudes"
" are only used for comparison, not for the design itself."
)
},
'min': {
'fo': ('d', 'N'),
'msg':
('a',
"Enter desired attenuation <b><i>A<sub>SB</sub></i></b> at "
"the corner of the stop band <b><i>F<sub>SB</sub></i></b>. "
"Choose the number of <b>stages</b>, the minimum order <b><i>M</i></b> "
"per stage will be determined. Passband specs are not regarded."
)
}
},
'LP': {
'man': {
'tspecs': ('u', {
'frq': ('u', 'F_PB', 'F_SB'),
'amp': ('u', 'A_PB', 'A_SB')
})
},
'min': {
'tspecs': ('a', {
'frq': ('a', 'F_PB', 'F_SB'),
'amp': ('a', 'A_PB', 'A_SB')
})
}
},
'HP': {
'man': {
'tspecs': ('u', {
'frq': ('u', 'F_SB', 'F_PB'),
'amp': ('u', 'A_SB', 'A_PB')
})
},
'min': {
'tspecs': ('a', {
'frq': ('a', 'F_SB', 'F_PB'),
'amp': ('a', 'A_SB', 'A_PB')
})
},
},
'BS': {
'man': {
'tspecs': ('u', {
'frq': ('u', 'F_PB', 'F_SB', 'F_SB2', 'F_PB2'),
'amp': ('u', 'A_PB', 'A_SB', 'A_PB2')
}),
'msg':
('a', "\nThis is not a proper band stop, it only lets pass"
" frequency components around DC and <i>f<sub>S</sub></i>/2."
" The order needs to be odd."),
}
},
'BP': {
'man': {
'tspecs': ('u', {
'frq': (
'u',
'F_SB',
'F_PB',
'F_PB2',
'F_SB2',
),
'amp': ('u', 'A_SB', 'A_PB', 'A_SB2')
}),
'msg':
('a', "\nThis is not a proper band pass, it only lets pass"
" frequency components around <i>f<sub>S</sub></i>/4."
" The order needs to be odd."),
}
},
}
self.info_doc = []
# self.info_doc.append('remez()\n=======')
# self.info_doc.append(sig.remez.__doc__)
# self.info_doc.append('remezord()\n==========')
# self.info_doc.append(remezord.__doc__)
#--------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter instance, fb.fil_inst.
"""
self.lbl_delays = QLabel("<b><i>M =</ i></ b>", self)
self.lbl_delays.setObjectName('wdg_lbl_ma_0')
self.led_delays = QLineEdit(self)
try:
self.led_delays.setText(str(fb.fil[0]['N']))
except KeyError:
self.led_delays.setText(str(self.delays))
self.led_delays.setObjectName('wdg_led_ma_0')
self.led_delays.setToolTip("Set number of delays per stage")
self.lbl_stages = QLabel("<b>Stages =</ b>", self)
self.lbl_stages.setObjectName('wdg_lbl_ma_1')
self.led_stages = QLineEdit(self)
self.led_stages.setText(str(self.stages))
self.led_stages.setObjectName('wdg_led_ma_1')
self.led_stages.setToolTip("Set number of stages ")
self.chk_norm = QCheckBox("Normalize", self)
self.chk_norm.setChecked(True)
self.chk_norm.setObjectName('wdg_chk_ma_2')
self.chk_norm.setToolTip("Normalize to| H_max = 1|")
self.layHWin = QHBoxLayout()
self.layHWin.setObjectName('wdg_layGWin')
self.layHWin.addWidget(self.lbl_delays)
self.layHWin.addWidget(self.led_delays)
self.layHWin.addStretch(1)
self.layHWin.addWidget(self.lbl_stages)
self.layHWin.addWidget(self.led_stages)
self.layHWin.addStretch(1)
self.layHWin.addWidget(self.chk_norm)
self.layHWin.setContentsMargins(0, 0, 0, 0)
# Widget containing all subwidgets (cmbBoxes, Labels, lineEdits)
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layHWin)
#----------------------------------------------------------------------
# SIGNALS & SLOTs
#----------------------------------------------------------------------
self.led_delays.editingFinished.connect(self._update_UI)
self.led_stages.editingFinished.connect(self._update_UI)
# fires when edited line looses focus or when RETURN is pressed
self.chk_norm.clicked.connect(self._update_UI)
#----------------------------------------------------------------------
self._load_dict() # get initial / last setting from dictionary
self._update_UI()
def _load_dict(self):
"""
Reload parameter(s) from filter dictionary (if they exist) and set
corresponding UI elements. load_dict() is called upon initialization
and when the filter is loaded from disk.
"""
if 'wdg_fil' in fb.fil[0] and 'ma' in fb.fil[0]['wdg_fil']:
wdg_fil_par = fb.fil[0]['wdg_fil']['ma']
if 'delays' in wdg_fil_par:
self.delays = wdg_fil_par['delays']
self.led_delays.setText(str(self.delays))
if 'stages' in wdg_fil_par:
self.stages = wdg_fil_par['stages']
self.led_stages.setText(str(self.stages))
if 'normalize' in wdg_fil_par:
self.chk_norm.setChecked(wdg_fil_par['normalize'])
def _update_UI(self):
"""
Update UI when line edit field is changed (here, only the text is read
and converted to integer) and resize the textfields according to content.
"""
self.delays = safe_eval(self.led_delays.text(),
self.delays,
return_type='int',
sign='pos')
self.led_delays.setText(str(self.delays))
self.stages = safe_eval(self.led_stages.text(),
self.stages,
return_type='int',
sign='pos')
self.led_stages.setText(str(self.stages))
self._store_entries()
def _store_entries(self):
"""
Store parameter settings in filter dictionary. Called from _update_UI()
and _save()
"""
if not 'wdg_fil' in fb.fil[0]:
fb.fil[0].update({'wdg_fil': {}})
fb.fil[0]['wdg_fil'].update({
'ma': {
'delays': self.delays,
'stages': self.stages,
'normalize': self.chk_norm.isChecked()
}
})
# sig_tx -> select_filter -> filter_specs
self.emit({'filt_changed': 'ma'})
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
"""
# N is total order, L is number of taps per stage
self.F_SB = fil_dict['F_SB']
self.A_SB = fil_dict['A_SB']
def _save(self, fil_dict):
"""
Save MA-filters both in 'zpk' and 'ba' format; no conversion has to be
performed except maybe deleting an 'sos' entry from an earlier
filter design.
"""
if 'zpk' in self.FRMT:
fil_save(fil_dict, self.zpk, 'zpk', __name__, convert=False)
if 'ba' in self.FRMT:
fil_save(fil_dict, self.b, 'ba', __name__, convert=False)
fil_convert(fil_dict, self.FRMT)
# always update filter dict and LineEdit, in case the design algorithm
# has changed the number of delays:
fil_dict['N'] = self.delays * self.stages # updated filter order
self.led_delays.setText(str(self.delays)) # updated number of delays
self._store_entries()
def calc_ma(self, fil_dict, rt='LP'):
"""
Calculate coefficients and P/Z for moving average filter based on
filter length L = N + 1 and number of cascaded stages and save the
result in the filter dictionary.
"""
b = 1.
k = 1.
L = self.delays + 1
if rt == 'LP':
b0 = np.ones(L) # h[n] = {1; 1; 1; ...}
i = np.arange(1, L)
norm = L
elif rt == 'HP':
b0 = np.ones(L)
b0[::2] = -1. # h[n] = {1; -1; 1; -1; ...}
i = np.arange(L)
if (L % 2 == 0): # even order, remove middle element
i = np.delete(i, round(L / 2.))
else: # odd order, shift by 0.5 and remove middle element
i = np.delete(i, int(L / 2.)) + 0.5
norm = L
elif rt == 'BP':
# N is even, L is odd
b0 = np.ones(L)
b0[1::2] = 0
b0[::4] = -1 # h[n] = {1; 0; -1; 0; 1; ... }
L = L + 1
i = np.arange(L) # create N + 2 zeros around the unit circle, ...
# ... remove first and middle element and rotate by L / 4
i = np.delete(i, [0, L // 2]) + L / 4
norm = np.sum(abs(b0))
elif rt == 'BS':
# N is even, L is odd
b0 = np.ones(L)
b0[1::2] = 0
L = L + 1
i = np.arange(
L) # create N + 2 zeros around the unit circle and ...
i = np.delete(i,
[0, L // 2]) # ... remove first and middle element
norm = np.sum(b0)
if self.delays > 1000:
if not qfilter_warning(None, self.delays * self.stages,
"Moving Average"):
return -1
z0 = np.exp(-2j * np.pi * i / L)
# calculate filter for multiple cascaded stages
for i in range(self.stages):
b = np.convolve(b0, b)
z = np.repeat(z0, self.stages)
# normalize filter to |H_max| = 1 if checked:
if self.chk_norm.isChecked():
b = b / (norm**self.stages)
k = 1. / norm**self.stages
p = np.zeros(len(z))
# store in class attributes for the _save method
self.zpk = [z, p, k]
self.b = b
self._save(fil_dict)
def LPman(self, fil_dict):
self._get_params(fil_dict)
self.calc_ma(fil_dict, rt='LP')
def LPmin(self, fil_dict):
self._get_params(fil_dict)
self.delays = int(
np.ceil(
1 /
(self.A_SB**(1 / self.stages) * np.sin(self.F_SB * np.pi))))
self.calc_ma(fil_dict, rt='LP')
def HPman(self, fil_dict):
self._get_params(fil_dict)
self.calc_ma(fil_dict, rt='HP')
def HPmin(self, fil_dict):
self._get_params(fil_dict)
self.delays = int(
np.ceil(1 / (self.A_SB**(1 / self.stages) * np.sin(
(0.5 - self.F_SB) * np.pi))))
self.calc_ma(fil_dict, rt='HP')
def BSman(self, fil_dict):
self._get_params(fil_dict)
self.delays = ceil_odd(self.delays) # enforce odd order
self.calc_ma(fil_dict, rt='BS')
def BPman(self, fil_dict):
self._get_params(fil_dict)
self.delays = ceil_odd(self.delays) # enforce odd order
self.calc_ma(fil_dict, rt='BP')
class Equiripple(QWidget):
FRMT = 'ba' # output format of filter design routines 'zpk' / 'ba' / 'sos'
# currently, only 'ba' is supported for equiripple routines
info = """
**Equiripple filters**
have the steepest rate of transition between the frequency response’s passband
and stopband of all FIR filters. This comes at the expense of a constant ripple
(equiripple) :math:`A_PB` and :math:`A_SB` in both pass and stop band.
The filter-coefficients are calculated in such a way that the transfer function
minimizes the maximum error (**Minimax** design) between the desired gain and the
realized gain in the specified frequency bands using the **Remez** exchange algorithm.
The filter design algorithm is known as **Parks-McClellan** algorithm, in
Matlab (R) it is called ``firpm``.
Manual filter order design requires specifying the frequency bands (:math:`F_PB`,
:math:`f_SB` etc.), the filter order :math:`N` and weight factors :math:`W_PB`,
:math:`W_SB` etc.) for individual bands.
The minimum order and the weight factors needed to fulfill the target specifications
is estimated from frequency and amplitude specifications using Ichige's algorithm.
**Design routines:**
``scipy.signal.remez()``, ``pyfda_lib.remezord()``
"""
sig_tx = pyqtSignal(object)
def __init__(self):
QWidget.__init__(self)
self.grid_density = 16
self.ft = 'FIR'
self.rt_dicts = ('com', )
self.rt_dict = {
'COM': {
'man': {
'fo': ('a', 'N'),
'msg':
('a',
"<span>Enter desired filter order <b><i>N</i></b>, corner "
"frequencies of pass and stop band(s), <b><i>F<sub>PB</sub></i></b>"
" and <b><i>F<sub>SB</sub></i></b> , and relative weight "
"values <b><i>W </i></b> (1 ... 10<sup>6</sup>) to specify how well "
"the bands are approximated.</span>")
},
'min': {
'fo': ('d', 'N'),
'msg':
('a',
"<span>Enter the maximum pass band ripple <b><i>A<sub>PB</sub></i></b>, "
"minimum stop band attenuation <b><i>A<sub>SB</sub></i></b> "
"and the corresponding corner frequencies of pass and "
"stop band(s), <b><i>F<sub>PB</sub></i></b> and "
"<b><i>F<sub>SB</sub></i></b> .</span>")
}
},
'LP': {
'man': {
'wspecs': ('a', 'W_PB', 'W_SB'),
'tspecs': ('u', {
'frq': ('a', 'F_PB', 'F_SB'),
'amp': ('u', 'A_PB', 'A_SB')
})
},
'min': {
'wspecs': ('d', 'W_PB', 'W_SB'),
'tspecs': ('a', {
'frq': ('a', 'F_PB', 'F_SB'),
'amp': ('a', 'A_PB', 'A_SB')
})
}
},
'HP': {
'man': {
'wspecs': ('a', 'W_SB', 'W_PB'),
'tspecs': ('u', {
'frq': ('a', 'F_SB', 'F_PB'),
'amp': ('u', 'A_SB', 'A_PB')
})
},
'min': {
'wspecs': ('d', 'W_SB', 'W_PB'),
'tspecs': ('a', {
'frq': ('a', 'F_SB', 'F_PB'),
'amp': ('a', 'A_SB', 'A_PB')
})
}
},
'BP': {
'man': {
'wspecs': ('a', 'W_SB', 'W_PB', 'W_SB2'),
'tspecs': ('u', {
'frq': ('a', 'F_SB', 'F_PB', 'F_PB2', 'F_SB2'),
'amp': ('u', 'A_SB', 'A_PB', 'A_SB2')
})
},
'min': {
'wspecs': ('d', 'W_SB', 'W_PB', 'W_SB2'),
'tspecs': ('a', {
'frq': ('a', 'F_SB', 'F_PB', 'F_PB2', 'F_SB2'),
'amp': ('a', 'A_SB', 'A_PB', 'A_SB2')
})
},
},
'BS': {
'man': {
'wspecs': ('a', 'W_PB', 'W_SB', 'W_PB2'),
'tspecs': ('u', {
'frq': ('a', 'F_PB', 'F_SB', 'F_SB2', 'F_PB2'),
'amp': ('u', 'A_PB', 'A_SB', 'A_PB2')
})
},
'min': {
'wspecs': ('d', 'W_PB', 'W_SB', 'W_PB2'),
'tspecs': ('a', {
'frq': ('a', 'F_PB', 'F_SB', 'F_SB2', 'F_PB2'),
'amp': ('a', 'A_PB', 'A_SB', 'A_PB2')
})
}
},
'HIL': {
'man': {
'wspecs': ('a', 'W_SB', 'W_PB', 'W_SB2'),
'tspecs': ('u', {
'frq': ('a', 'F_SB', 'F_PB', 'F_PB2', 'F_SB2'),
'amp': ('u', 'A_SB', 'A_PB', 'A_SB2')
})
}
},
'DIFF': {
'man': {
'wspecs': ('a', 'W_PB'),
'tspecs': ('u', {
'frq': ('a', 'F_PB'),
'amp': ('i', )
}),
'msg':
('a',
"Enter the max. frequency up to where the differentiator "
"works.")
}
}
}
self.info_doc = []
self.info_doc.append('remez()\n=======')
self.info_doc.append(sig.remez.__doc__)
self.info_doc.append('remezord()\n==========')
self.info_doc.append(remezord.__doc__)
#--------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter instance, fb.fil_inst.
"""
self.lbl_remez_1 = QLabel("Grid Density", self)
self.lbl_remez_1.setObjectName('wdg_lbl_remez_1')
self.led_remez_1 = QLineEdit(self)
self.led_remez_1.setText(str(self.grid_density))
self.led_remez_1.setObjectName('wdg_led_remez_1')
self.led_remez_1.setToolTip(
"Number of frequency points for Remez algorithm. Increase the\n"
"number to reduce frequency overshoot in the transition region.")
self.layHWin = QHBoxLayout()
self.layHWin.setObjectName('wdg_layGWin')
self.layHWin.addWidget(self.lbl_remez_1)
self.layHWin.addWidget(self.led_remez_1)
self.layHWin.setContentsMargins(0, 0, 0, 0)
# Widget containing all subwidgets (cmbBoxes, Labels, lineEdits)
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layHWin)
#----------------------------------------------------------------------
# SIGNALS & SLOTs
#----------------------------------------------------------------------
self.led_remez_1.editingFinished.connect(self._update_UI)
# fires when edited line looses focus or when RETURN is pressed
#----------------------------------------------------------------------
self._load_dict() # get initial / last setting from dictionary
self._update_UI()
def _update_UI(self):
"""
Update UI when line edit field is changed (here, only the text is read
and converted to integer) and store parameter settings in filter
dictionary
"""
self.grid_density = safe_eval(self.led_remez_1.text(),
self.grid_density,
return_type='int',
sign='pos')
self.led_remez_1.setText(str(self.grid_density))
if not 'wdg_fil' in fb.fil[0]:
fb.fil[0].update({'wdg_fil': {}})
fb.fil[0]['wdg_fil'].update(
{'equiripple': {
'grid_density': self.grid_density
}})
# sig_tx -> select_filter -> filter_specs
self.sig_tx.emit({'sender': __name__, 'filt_changed': 'equiripple'})
def _load_dict(self):
"""
Reload parameter(s) from filter dictionary (if they exist) and set
corresponding UI elements. _load_dict() is called upon initialization
and when the filter is loaded from disk.
"""
if 'wdg_fil' in fb.fil[0] and 'equiripple' in fb.fil[0]['wdg_fil']:
wdg_fil_par = fb.fil[0]['wdg_fil']['equiripple']
if 'grid_density' in wdg_fil_par:
self.grid_density = wdg_fil_par['grid_density']
self.led_remez_1.setText(str(self.grid_density))
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
"""
self.N = fil_dict['N'] + 1 # remez algorithms expects number of taps
# which is larger by one than the order!!
self.F_PB = fil_dict['F_PB']
self.F_SB = fil_dict['F_SB']
self.F_PB2 = fil_dict['F_PB2']
self.F_SB2 = fil_dict['F_SB2']
# remez amplitude specs are linear (not in dBs)
self.A_PB = fil_dict['A_PB']
self.A_PB2 = fil_dict['A_PB2']
self.A_SB = fil_dict['A_SB']
self.A_SB2 = fil_dict['A_SB2']
self.alg = 'ichige'
def _test_N(self):
"""
Warn the user if the calculated order is too high for a reasonable filter
design.
"""
if self.N > 2000:
return qfilter_warning(self, self.N, "Equiripple")
else:
return True
def _save(self, fil_dict, arg):
"""
Convert between poles / zeros / gain, filter coefficients (polynomes)
and second-order sections and store all available formats in the passed
dictionary 'fil_dict'.
"""
try:
fil_save(fil_dict, arg, self.FRMT, __name__)
except Exception as e:
# catch exception due to malformatted coefficients:
logger.error("While saving the equiripple filter design, "
"the following error occurred:\n{0}".format(e))
return -1
if str(fil_dict['fo']) == 'min':
fil_dict['N'] = self.N - 1 # yes, update filterbroker
def LPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.remez(self.N, [0, self.F_PB, self.F_SB, 0.5], [1, 0],
weight=[fil_dict['W_PB'], fil_dict['W_SB']],
fs=1,
grid_density=self.grid_density))
def LPmin(self, fil_dict):
self._get_params(fil_dict)
(self.N, F, A, W) = remezord([self.F_PB, self.F_SB], [1, 0],
[self.A_PB, self.A_SB],
fs=1,
alg=self.alg)
if not self._test_N():
return -1
fil_dict['W_PB'] = W[0]
fil_dict['W_SB'] = W[1]
self._save(
fil_dict,
sig.remez(self.N,
F, [1, 0],
weight=W,
fs=1,
grid_density=self.grid_density))
def HPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
if (self.N % 2 == 0): # even order, use odd symmetry (type III)
self._save(
fil_dict,
sig.remez(self.N, [0, self.F_SB, self.F_PB, 0.5], [0, 1],
weight=[fil_dict['W_SB'], fil_dict['W_PB']],
fs=1,
type='hilbert',
grid_density=self.grid_density))
else: # odd order,
self._save(
fil_dict,
sig.remez(self.N, [0, self.F_SB, self.F_PB, 0.5], [0, 1],
weight=[fil_dict['W_SB'], fil_dict['W_PB']],
fs=1,
type='bandpass',
grid_density=self.grid_density))
def HPmin(self, fil_dict):
self._get_params(fil_dict)
(self.N, F, A, W) = remezord([self.F_SB, self.F_PB], [0, 1],
[self.A_SB, self.A_PB],
fs=1,
alg=self.alg)
if not self._test_N():
return -1
# self.N = ceil_odd(N) # enforce odd order
fil_dict['W_SB'] = W[0]
fil_dict['W_PB'] = W[1]
if (self.N % 2 == 0): # even order
self._save(
fil_dict,
sig.remez(self.N,
F, [0, 1],
weight=W,
fs=1,
type='hilbert',
grid_density=self.grid_density))
else:
self._save(
fil_dict,
sig.remez(self.N,
F, [0, 1],
weight=W,
fs=1,
type='bandpass',
grid_density=self.grid_density))
# For BP and BS, F_PB and F_SB have two elements each
def BPman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.remez(
self.N, [0, self.F_SB, self.F_PB, self.F_PB2, self.F_SB2, 0.5],
[0, 1, 0],
weight=[fil_dict['W_SB'], fil_dict['W_PB'], fil_dict['W_SB2']],
fs=1,
grid_density=self.grid_density))
def BPmin(self, fil_dict):
self._get_params(fil_dict)
(self.N, F, A,
W) = remezord([self.F_SB, self.F_PB, self.F_PB2, self.F_SB2],
[0, 1, 0], [self.A_SB, self.A_PB, self.A_SB2],
fs=1,
alg=self.alg)
if not self._test_N():
return -1
fil_dict['W_SB'] = W[0]
fil_dict['W_PB'] = W[1]
fil_dict['W_SB2'] = W[2]
self._save(
fil_dict,
sig.remez(self.N,
F, [0, 1, 0],
weight=W,
fs=1,
grid_density=self.grid_density))
def BSman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self.N = round_odd(self.N) # enforce odd order
self._save(
fil_dict,
sig.remez(
self.N, [0, self.F_PB, self.F_SB, self.F_SB2, self.F_PB2, 0.5],
[1, 0, 1],
weight=[fil_dict['W_PB'], fil_dict['W_SB'], fil_dict['W_PB2']],
fs=1,
grid_density=self.grid_density))
def BSmin(self, fil_dict):
self._get_params(fil_dict)
(N, F, A, W) = remezord([self.F_PB, self.F_SB, self.F_SB2, self.F_PB2],
[1, 0, 1], [self.A_PB, self.A_SB, self.A_PB2],
fs=1,
alg=self.alg)
self.N = round_odd(N) # enforce odd order
if not self._test_N():
return -1
fil_dict['W_PB'] = W[0]
fil_dict['W_SB'] = W[1]
fil_dict['W_PB2'] = W[2]
self._save(
fil_dict,
sig.remez(self.N,
F, [1, 0, 1],
weight=W,
fs=1,
grid_density=self.grid_density))
def HILman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.remez(
self.N, [0, self.F_SB, self.F_PB, self.F_PB2, self.F_SB2, 0.5],
[0, 1, 0],
weight=[fil_dict['W_SB'], fil_dict['W_PB'], fil_dict['W_SB2']],
fs=1,
type='hilbert',
grid_density=self.grid_density))
def DIFFman(self, fil_dict):
self._get_params(fil_dict)
if not self._test_N():
return -1
self.N = ceil_even(self.N) # enforce even order
if self.F_PB < 0.1:
logger.warning(
"Bandwidth for pass band ({0}) is too low, inreasing to 0.1".
format(self.F_PB))
self.F_PB = 0.1
fil_dict['F_PB'] = self.F_PB
self.sig_tx.emit({
'sender': __name__,
'specs_changed': 'equiripple'
})
self._save(
fil_dict,
sig.remez(self.N, [0, self.F_PB], [np.pi * fil_dict['W_PB']],
fs=1,
type='differentiator',
grid_density=self.grid_density))
class EllipZeroPhz(QWidget):
# Since we are also using poles/residues -> let's force zpk
FRMT = 'zpk'
info = """
**Elliptic filters with zero phase**
(also known as Cauer filters) have the steepest rate of transition between the
frequency response’s passband and stopband of all IIR filters. This comes
at the expense of a constant ripple (equiripple) :math:`A_PB` and :math:`A_SB`
in both pass and stop band. Ringing of the step response is increased in
comparison to Chebychev filters.
As the passband ripple :math:`A_PB` approaches 0, the elliptical filter becomes
a Chebyshev type II filter. As the stopband ripple :math:`A_SB` approaches 0,
it becomes a Chebyshev type I filter. As both approach 0, becomes a Butterworth
filter (butter).
For the filter design, the order :math:`N`, minimum stopband attenuation
:math:`A_SB` and the critical frequency / frequencies :math:`F_PB` where the
gain first drops below the maximum passband ripple :math:`-A_PB` have to be specified.
The ``ellipord()`` helper routine calculates the minimum order :math:`N` and
critical passband frequency :math:`F_C` from pass and stop band specifications.
The Zero Phase Elliptic Filter squares an elliptic filter designed in
a way to produce the required Amplitude specifications. So initially the
amplitude specs design an elliptic filter with the square root of the amp specs.
The filter is then squared to produce a zero phase filter.
The filter coefficients are applied to the signal data in a backward and forward
time fashion. This filter can only be applied to stored signal data (not
real-time streaming data that comes in a forward time order).
We are forcing the order N of the filter to be even. This simplifies the poles/zeros
to be complex (no real values).
**Design routines:**
``scipy.signal.ellip()``, ``scipy.signal.ellipord()``
"""
sig_tx = pyqtSignal(object)
def __init__(self):
QWidget.__init__(self)
self.ft = 'IIR'
c = Common()
self.rt_dict = c.rt_base_iir
self.rt_dict_add = {
'COM': {
'man': {
'msg':
('a',
"Enter the filter order <b><i>N</i></b>, the minimum stop "
"band attenuation <b><i>A<sub>SB</sub></i></b> and frequency or "
"frequencies <b><i>F<sub>C</sub></i></b> where gain first drops "
"below the max passband ripple <b><i>-A<sub>PB</sub></i></b> ."
)
}
},
'LP': {
'man': {},
'min': {}
},
'HP': {
'man': {},
'min': {}
},
'BS': {
'man': {},
'min': {}
},
'BP': {
'man': {},
'min': {}
},
}
self.info_doc = []
self.info_doc.append('ellip()\n========')
self.info_doc.append(sig.ellip.__doc__)
self.info_doc.append('ellipord()\n==========')
self.info_doc.append(ellipord.__doc__)
#--------------------------------------------------------------------------
def construct_UI(self):
"""
Create additional subwidget(s) needed for filter design:
These subwidgets are instantiated dynamically when needed in
select_filter.py using the handle to the filter instance, fb.fil_inst.
"""
# =============================================================================
# self.chkComplex = QCheckBox("ComplexFilter", self)
# self.chkComplex.setToolTip("Designs BP or BS Filter for complex data.")
# self.chkComplex.setObjectName('wdg_lbl_el')
# self.chkComplex.setChecked(False)
#
# =============================================================================
self.butSave = QPushButton(self)
self.butSave.setText("SAVE")
self.butSave.setToolTip("Save filter in proprietary format")
#--------------------------------------------------
# Layout for filter optional subwidgets
self.layHWin = QHBoxLayout()
self.layHWin.setObjectName('wdg_layGWin')
#self.layHWin.addWidget(self.chkComplex)
self.layHWin.addWidget(self.butSave)
self.layHWin.addStretch()
self.layHWin.setContentsMargins(0, 0, 0, 0)
# Widget containing all subwidgets
self.wdg_fil = QWidget(self)
self.wdg_fil.setObjectName('wdg_fil')
self.wdg_fil.setLayout(self.layHWin)
self.butSave.clicked.connect(self.save_filter)
def _get_params(self, fil_dict):
"""
Translate parameters from the passed dictionary to instance
parameters, scaling / transforming them if needed.
For zero phase filter, we take square root of amplitude specs
since we later square filter. Define design around smallest amp spec
"""
# Frequencies are normalized to f_Nyq = f_S/2, ripple specs are in dB
self.analog = False # set to True for analog filters
self.manual = False # default is normal design
self.N = int(fil_dict['N'])
# force N to be even
if (self.N % 2) == 1:
self.N += 1
self.F_PB = fil_dict['F_PB'] * 2
self.F_SB = fil_dict['F_SB'] * 2
self.F_PB2 = fil_dict['F_PB2'] * 2
self.F_SB2 = fil_dict['F_SB2'] * 2
self.F_PBC = None
# find smallest spec'd linear value and rewrite dictionary
ampPB = fil_dict['A_PB']
ampSB = fil_dict['A_SB']
# take square roots of amp specs so resulting squared
# filter will meet specifications
if (ampPB < ampSB):
ampSB = sqrt(ampPB)
ampPB = sqrt(1 + ampPB) - 1
else:
ampPB = sqrt(1 + ampSB) - 1
ampSB = sqrt(ampSB)
self.A_PB = lin2unit(ampPB, 'IIR', 'A_PB', unit='dB')
self.A_SB = lin2unit(ampSB, 'IIR', 'A_SB', unit='dB')
#logger.warning("design with "+str(self.A_PB)+","+str(self.A_SB))
# ellip filter routines support only one amplitude spec for
# pass- and stop band each
if str(fil_dict['rt']) == 'BS':
fil_dict['A_PB2'] = self.A_PB
elif str(fil_dict['rt']) == 'BP':
fil_dict['A_SB2'] = self.A_SB
# partial fraction expansion to define residue vector
def _partial(self, k, p, z, norder):
# create diff array
diff = p - z
# now compute residual vector
cone = complex(1., 0.)
residues = zeros(norder, complex)
for i in range(norder):
residues[i] = k * (diff[i] / p[i])
for j in range(norder):
if (j != i):
residues[i] = residues[i] * (cone + diff[j] /
(p[i] - p[j]))
# now compute DC term for new expansion
sumRes = 0.
for i in range(norder):
sumRes = sumRes + residues[i].real
dc = k - sumRes
return (dc, residues)
#
# Take a causal filter and square it. The result has the square
# of the amplitude response of the input, and zero phase. Filter
# is noncausal.
# Input:
# k - gain in pole/zero form
# p - numpy array of poles
# z - numpy array of zeros
# g - gain in pole/residue form
# r - numpy array of residues
# nn- order of filter
# Output:
# kn - new gain (pole/zero)
# pn - new poles
# zn - new zeros (numpy array)
# gn - new gain (pole/residue)
# rn - new residues
def _sqCausal(self, k, p, z, g, r, nn):
# Anticausal poles have conjugate-reciprocal symmetry
# Starting anticausal residues are conjugates (adjusted below)
pA = conj(1. / p) # antiCausal poles
zA = conj(z) # antiCausal zeros (store reciprocal)
rA = conj(r) # antiCausal residues (to start)
rC = zeros(nn, complex)
# Adjust residues. Causal part first.
for j in range(nn):
# Evaluate the anticausal filter at each causal pole
tmpx = rA / (1. - p[j] / pA)
ztmp = g + sum(tmpx)
# Adjust residue
rC[j] = r[j] * ztmp
# anticausal residues are just conjugates of causal residues
# r3 = np.conj(r2)
# Compute the constant term
dc2 = (g + sum(r)) * g - sum(rC)
# Populate output (2nn elements)
gn = dc2.real
# Drop complex poles/residues in LHP, keep only UHP
pA = conj(p) #store AntiCasual pole (reciprocal)
p0 = zeros(int(nn / 2), complex)
r0 = zeros(int(nn / 2), complex)
cnt = 0
for j in range(nn):
if (p[j].imag > 0.0):
p0[cnt] = p[j]
r0[cnt] = rC[j]
cnt = cnt + 1
# Let operator know we squared filter
# logger.info('After squaring filter, order: '+str(nn*2))
# For now and our case, only store causal residues
# Filters are symmetric and can generate antiCausal residues
return (pA, zA, gn, p0, r0)
def _test_N(self):
"""
Warn the user if the calculated order is too high for a reasonable filter
design.
"""
if self.N > 30:
return qfilter_warning(self, self.N, "Zero-phase Elliptic")
else:
return True
# custom save of filter dictionary
def _save(self, fil_dict, arg):
"""
First design initial elliptic filter meeting sqRoot Amp specs;
- Then create residue vector from poles/zeros;
- Then square filter (k,p,z and dc,p,r) to get zero phase filter;
- Then Convert results of filter design to all available formats (pz, pr, ba, sos)
and store them in the global filter dictionary.
Corner frequencies and order calculated for minimum filter order are
also stored to allow for an easy subsequent manual filter optimization.
"""
fil_save(fil_dict, arg, self.FRMT, __name__)
# For min. filter order algorithms, update filter dict with calculated
# new values for filter order N and corner frequency(s) F_PBC
fil_dict['N'] = self.N
if str(fil_dict['fo']) == 'min':
if str(fil_dict['rt']) == 'LP' or str(fil_dict['rt']) == 'HP':
# HP or LP - single corner frequency
fil_dict['F_PB'] = self.F_PBC / 2.
else: # BP or BS - two corner frequencies
fil_dict['F_PB'] = self.F_PBC[0] / 2.
fil_dict['F_PB2'] = self.F_PBC[1] / 2.
# Now generate poles/residues for custom file save of new parameters
if (not self.manual):
z = fil_dict['zpk'][0]
p = fil_dict['zpk'][1]
k = fil_dict['zpk'][2]
n = len(z)
gain, residues = self._partial(k, p, z, n)
pA, zA, gn, pC, rC = self._sqCausal(k, p, z, gain, residues, n)
fil_dict['rpk'] = [rC, pC, gn]
# save antiCausal b,a (nonReciprocal) also [easier to compute h(n)
try:
fil_dict['baA'] = sig.zpk2tf(zA, pA, k)
except Exception as e:
logger.error(e)
# 'rpk' is our signal that this is a non-Causal filter with zero phase
# inserted into fil dictionary after fil_save and convert
# sig_tx -> select_filter -> filter_specs
self.sig_tx.emit({'sender': __name__, 'filt_changed': 'ellip_zero'})
#------------------------------------------------------------------------------
def save_filter(self):
file_filters = ("Text file pole/residue (*.txt_rpk)")
dlg = QFD(self)
# return selected file name (with or without extension) and filter (Linux: full text)
file_name, file_type = dlg.getSaveFileName_(caption="Save filter as",
directory=dirs.save_dir,
filter=file_filters)
file_name = str(file_name) # QString -> str() needed for Python 2.x
# Qt5 has QFileDialog.mimeTypeFilters(), but under Qt4 the mime type cannot
# be extracted reproducibly across file systems, so it is done manually:
for t in extract_file_ext(
file_filters): # get a list of file extensions
if t in str(file_type):
file_type = t # return the last matching extension
if file_name != "": # cancelled file operation returns empty string
# strip extension from returned file name (if any) + append file type:
file_name = os.path.splitext(file_name)[0] + file_type
file_type_err = False
try:
# save as a custom residue/pole text output for apply with custom tool
# make sure we have the residues
if 'rpk' in fb.fil[0]:
with io.open(file_name, 'w', encoding="utf8") as f:
self.file_dump(f)
else:
file_type_err = True
logger.error(
'Filter has no residues/poles, cannot save as *.txt_rpk file'
)
if not file_type_err:
logger.info('Successfully saved filter as\n\t"{0}"'.format(
file_name))
dirs.save_dir = os.path.dirname(file_name) # save new dir
except IOError as e:
logger.error('Failed saving "{0}"!\n{1}'.format(file_name, e))
#------------------------------------------------------------------------------
def file_dump(self, fOut):
"""
Dump file out in custom text format that apply tool can read to know filter coef's
"""
# Fixed format widths for integers and doubles
intw = '10'
dblW = 27
frcW = 20
# Fill up character string with filter output
filtStr = '# IIR filter\n'
# parameters that made filter (choose smallest eps)
# Amp is stored in Volts (linear units)
# the second amp terms aren't really used (for ellip filters)
FA_PB = fb.fil[0]['A_PB']
FA_SB = fb.fil[0]['A_SB']
FAmp = min(FA_PB, FA_SB)
# Freq terms in radians so move from -1:1 to -pi:pi
f_lim = fb.fil[0]['freqSpecsRange']
f_unit = fb.fil[0]['freq_specs_unit']
F_S = fb.fil[0]['f_S']
if fb.fil[0]['freq_specs_unit'] == 'f_S':
F_S = F_S * 2
F_SB = fb.fil[0]['F_SB'] * F_S * np.pi
F_SB2 = fb.fil[0]['F_SB2'] * F_S * np.pi
F_PB = fb.fil[0]['F_PB'] * F_S * np.pi
F_PB2 = fb.fil[0]['F_PB2'] * F_S * np.pi
# Determine pass/stop bands depending on filter response type
passMin = []
passMax = []
stopMin = []
stopMax = []
if fb.fil[0]['rt'] == 'LP':
passMin = [-F_PB, 0, 0]
passMax = [F_PB, 0, 0]
stopMin = [-np.pi, F_SB, 0]
stopMax = [-F_SB, np.pi, 0]
f1 = F_PB
f2 = F_SB
f3 = f4 = 0
Ftype = 1
Fname = 'Low_Pass'
if fb.fil[0]['rt'] == 'HP':
passMin = [-np.pi, F_PB, 0]
passMax = [-F_PB, np.pi, 0]
stopMin = [-F_SB, 0, 0]
stopMax = [F_SB, 0, 0]
f1 = F_SB
f2 = F_PB
f3 = f4 = 0
Ftype = 2
Fname = 'Hi_Pass'
if fb.fil[0]['rt'] == 'BS':
passMin = [-np.pi, -F_PB, F_PB2]
passMax = [-F_PB2, F_PB, np.pi]
stopMin = [-F_SB2, F_SB, 0]
stopMax = [-F_SB, F_SB2, 0]
f1 = F_PB
f2 = F_SB
f3 = F_SB2
f4 = F_PB2
Ftype = 4
Fname = 'Band_Stop'
if fb.fil[0]['rt'] == 'BP':
passMin = [-F_PB2, F_PB, 0]
passMax = [-F_PB, F_PB2, 0]
stopMin = [-np.pi, -F_SB, F_SB2]
stopMax = [-F_SB2, F_SB, np.pi]
f1 = F_SB
f2 = F_PB
f3 = F_PB2
f4 = F_SB2
Ftype = 3
Fname = 'Band_Pass'
filtStr = filtStr + '{:{align}{width}}'.format(
'10', align='>', width=intw) + ' IIRFILT_4SYM\n'
filtStr = filtStr + '{:{align}{width}}'.format(
str(Ftype), align='>', width=intw) + ' ' + Fname + '\n'
filtStr = filtStr + '{:{d}.{p}f}'.format(FAmp, d=dblW, p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(passMin[0], d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(passMax[0], d=dblW,
p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(passMin[1], d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(passMax[1], d=dblW,
p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(passMin[2], d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(passMax[2], d=dblW,
p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(stopMin[0], d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(stopMax[0], d=dblW,
p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(stopMin[1], d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(stopMax[1], d=dblW,
p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(stopMin[2], d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(stopMax[2], d=dblW,
p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(f1, d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(f2, d=dblW, p=frcW) + '\n'
filtStr = filtStr + '{: {d}.{p}f}'.format(f3, d=dblW, p=frcW)
filtStr = filtStr + '{: {d}.{p}f}'.format(f4, d=dblW, p=frcW) + '\n'
# move pol/res/gain into terms we need
Fdc = fb.fil[0]['rpk'][2]
rC = fb.fil[0]['rpk'][0]
pC = fb.fil[0]['rpk'][1]
Fnum = len(pC)
# Gain term
filtStr = filtStr + '{: {d}.{p}e}'.format(Fdc, d=dblW, p=frcW) + '\n'
# Real pole count inside the unit circle (none of these)
filtStr = filtStr + '{:{align}{width}}'.format(
str(0), align='>', width=intw) + '\n'
# Complex pole/res count inside the unit circle
filtStr = filtStr + '{:{i}d}'.format(Fnum, i=intw) + '\n'
# Now dump poles/residues
for j in range(Fnum):
filtStr = filtStr + '{:{i}d}'.format(j, i=intw) + ' '
filtStr = filtStr + '{: {d}.{p}e}'.format(
rC[j].real, d=dblW, p=frcW) + ' '
filtStr = filtStr + '{: {d}.{p}e}'.format(
rC[j].imag, d=dblW, p=frcW) + ' '
filtStr = filtStr + '{: {d}.{p}e}'.format(
pC[j].real, d=dblW, p=frcW) + ' '
filtStr = filtStr + '{: {d}.{p}e}'.format(
pC[j].imag, d=dblW, p=frcW) + '\n'
# Real pole count outside the unit circle (none of these)
filtStr = filtStr + '{:{align}{width}}'.format(
str(0), align='>', width=intw) + '\n'
# Complex pole count outside the unit circle (none of these)
filtStr = filtStr + '{:{align}{width}}'.format(
str(0), align='>', width=intw) + '\n'
# Now write huge text string to file
fOut.write(filtStr)
#------------------------------------------------------------------------------
#
# DESIGN ROUTINES
#
#------------------------------------------------------------------------------
# LP: F_PB < F_stop -------------------------------------------------------
def LPmin(self, fil_dict):
"""Elliptic LP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,
self.F_SB,
self.A_PB,
self.A_SB,
analog=self.analog)
# force even N
if (self.N % 2) == 1:
self.N += 1
if not self._test_N():
return -1
#logger.warning("and "+str(self.F_PBC) + " " + str(self.N))
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='low',
analog=self.analog,
output=self.FRMT))
def LPman(self, fil_dict):
"""Elliptic LP filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PB,
btype='low',
analog=self.analog,
output=self.FRMT))
# HP: F_stop < F_PB -------------------------------------------------------
def HPmin(self, fil_dict):
"""Elliptic HP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord(self.F_PB,
self.F_SB,
self.A_PB,
self.A_SB,
analog=self.analog)
# force even N
if (self.N % 2) == 1:
self.N += 1
if not self._test_N():
return -1
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='highpass',
analog=self.analog,
output=self.FRMT))
def HPman(self, fil_dict):
"""Elliptic HP filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PB,
btype='highpass',
analog=self.analog,
output=self.FRMT))
# For BP and BS, F_XX have two elements each, A_XX has only one
# BP: F_SB[0] < F_PB[0], F_SB[1] > F_PB[1] --------------------------------
def BPmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2],
self.A_PB,
self.A_SB,
analog=self.analog)
#logger.warning(" "+str(self.F_PBC) + " " + str(self.N))
if (self.N % 2) == 1:
self.N += 1
if not self._test_N():
return -1
#logger.warning("-"+str(self.F_PBC) + " " + str(self.A_SB))
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='bandpass',
analog=self.analog,
output=self.FRMT))
def BPman(self, fil_dict):
"""Elliptic BP filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB, [self.F_PB, self.F_PB2],
btype='bandpass',
analog=self.analog,
output=self.FRMT))
# BS: F_SB[0] > F_PB[0], F_SB[1] < F_PB[1] --------------------------------
def BSmin(self, fil_dict):
"""Elliptic BP filter, minimum order"""
self._get_params(fil_dict)
self.N, self.F_PBC = ellipord([self.F_PB, self.F_PB2],
[self.F_SB, self.F_SB2],
self.A_PB,
self.A_SB,
analog=self.analog)
# force even N
if (self.N % 2) == 1:
self.N += 1
if not self._test_N():
return -1
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB,
self.F_PBC,
btype='bandstop',
analog=self.analog,
output=self.FRMT))
def BSman(self, fil_dict):
"""Elliptic BS filter, manual order"""
self._get_params(fil_dict)
if not self._test_N():
return -1
self._save(
fil_dict,
sig.ellip(self.N,
self.A_PB,
self.A_SB, [self.F_PB, self.F_PB2],
btype='bandstop',
analog=self.analog,
output=self.FRMT))